Effect of injection of adult mouse peritoneal macrophages on suppressor cell activity in neonatal mice

Injection of adult mouse peritoneal exudate cells into newborn mice results in a premature decrease of splenic suppressor cell activity in the neonates. The effect becomes apparent 4–5 days after ip injection of 10–15 × 10⁶ thioglycollate-induced peritoneal exudate cells into mice on the day of birth. The macrophage in the peritoneal exudate is the responsible cell type. The effect is not H-2 restricted or strain limited. Heat-killed peritoneal exudate cells or peritoneal cells from unstimulated donors can also decrease neonatal suppressor cell activity prematurely. Adult spleen cells, injected into neonatal mice, do not affect suppressor cell activity. The data are discussed in light of the hypothesis that macrophages control suppressor activity in neonatal mice and that an increase in the number and/or function of macrophages shortly after birth results in a decrease in the number and/or function of suppressor cells, allowing for immunological competence to emerge.     

Macrophages in the Small Intestinal Muscularis Externa of Embryos, Newborn and Adult Germ-Free Mice

Previously, we demonstrated the presence of a constant and regularly distributed macrophage population of ramified cells in the intestinal muscle layers of smaller rodents. The function of these resident macrophages under normal conditions remains unknown. Histochemistry, immunohistochemistry and electron microscopy were applied to the muscularis externa of 15- and 17-day-old embryos, 2-day-old mice, adult germ-free and conventional mice. Since lipopolysaccharides (LPS) activates macrophages and inflammation affects gut motility, LPS-treated mice were also included in the study. Two macrophage antibodies, F4/80 and 2F8 were used to demonstrate the presence of macrophages in the muscle layers. The localization was confirmed by electron microscopy. In contrast to conventional adult mice, the muscle layers in embryos, newborn and germ-free adult mice were devoid of class II MHC antigen reactive cells. The acid phosphatase reaction and antibodies directed towards a lysosomal protein (Lamp-2) were used in order to verify other activation markers. None of these showed specific staining of the muscularis macrophages. Only LPS-treated adult mice showed iNOS-positive cells in whole mounts. We conclude that the characteristic organization and distribution of muscularis macrophages in adult mice are also present in embryos, newborn and germ-free mice and thus develop independently of foreign antigens. Further, these macrophages are truly resident and appear to have differential responses to exogene stimuli.     

Effect of capsular polysaccharide of Klebsiella pneumoniae on the differentiation and functional capacity of macrophages cultured in vitro.

The effect of the capsular polysaccharide of Klebsiella pneumoniae (CPS-K) on the differentiation and functional capacity of macrophages cultured in vitro from various lymphoid tissues was investigated. In cultures of peritoneal cells, the number of macrophages did not change throughout incubation periods of from 1 hr to 3 days, and the addition of CPS-K had no affect. It appears therefore that CPS-K does not exhibit cytotoxic effects on macrophages. In cultures of spleen cells, only a small number of macrophages appeared within 1 hr, but the number of macrophages increased during further incubation. The addition of CPS-K to cultures of spleen cells at the start of incubation suppressed markedly the increase in the numbers of macrophage. This finding indicates that CPS-K blocks the process of the generation of macrophages, probably from their precursor cells in cultures of spleen cells. Only a small number of macrophages appeared in cultures of thymocytes or lymph node cells either with or without CPS-K. The phagocytic capacity of either peritoneal macrophages or macrophages generated in cultures of spleen cells was activated during incubation in vitro. Macrophages cultured in the presence of CPS-K for 24 hr or longer appeared to have an enhanced phagocytic activity, although the enhancement of their phagocytic activity by the addition of CPS-K was less marked in cultures of spleen cells than in those of peritoneal macrophages. Morphologically, macrophages in both cultures of peritoneal cells and spleen cells incubated in the presence of CPS-K for 4 days possessed much longer cytoplasmic processes than those incubated in the absence of CPS-K. From the present study, it appears that CPS-K exhibits dual effects on macrophage precursor cells and macrophages, a blocking effect on the differentiation from the former to the latter and an enhancing effect on the functional capacity of the latter.     

Correlation between the lipopolysaccharide response of mice and the capacity of mouse peritoneal cells to transfer an antiviral state. Role of endogenous interferon

Freshly harvested mouse peritoneal cells, from normal lipopolysaccharide (LPS)-responsive (Lpsn) mice, were capable of transferring an antiviral state (to vesicular stomatitis virus) to "in vitro aged" mouse macrophages permissive for viral replication. The transfer of the antiviral state was completely abrogated by addition of antibody to interferon (IFN)-alpha/beta in the co-culture medium. In contrast, even large numbers of donor peritoneal cells from LPS-hyporesponsive (Lpsd) C3H/HeJ and C57BL/10ScCR mice did not transfer an antiviral state to target cells. Although peritoneal macrophages from Lpsd mice did not transfer an antiviral state to target cells, they were nevertheless found to be in an antiviral state when first placed in culture. Injection of mice with antibody to mouse IFN-alpha/beta rendered peritoneal macrophages from both Lpsn and Lpsd mice permissive for vesicular stomatitis virus. The decay of this initial antiviral state in peritoneal macrophages during in vitro culture was far more rapid for Lpsd mice than for normal mice. Addition of antibody to mouse IFN-alpha/beta markedly enhanced the in vitro decay of the antiviral state of peritoneal macrophages. Treatment of total peritoneal cells from Lpsn mice with LPS resulted in IFN production, whereas IFN was not detected in the cellfree medium of LPS-treated peritoneal cells from Lpsd C3H/HeJ and C57BL/10ScCR mice. Genetic studies with F1 hybrids between Lpsn and Lpsd mice and with Lpsn and Lpsd recombinant inbred strains revealed a striking correlation between the capacity of peritoneal cells to transfer an antiviral state and their capacity to produce IFN after stimulation with LPS, suggesting that closely linked, if not identical, genes are in some way involved in the transfer of antiviral state as well as in the LPS response by peritoneal cells of normal mice.     

Immune reactivity in SL2 lymphoma-bearing mice compared with SL2-immunized mice

Summary We have studied the rather paradoxical phenomenon of the growth of an antigenic tumor in an immunocomponent host. This phenomenon was studied by comparing (a) the lymphocyte reactivity and (b) the macrophage cytotoxicity, during SL2 growth in DBA/2 mice (SL2-bearing mice) and in DBA/2 mice immunized against SL2 tumor cells (SL2-immune mice). Immune mice rejected a challenge of tumor cells. The immune T-lymphocytes rendered macrophages cytotoxic (arming) and were able to transfer tumor resistance to naive animals. Nonimmunized mice did not reject a challenge of SL2 cells. In these tumor-bearing mice various forms of immune reactivity were tested. Lymphocytes with the capacity to arm macrophages could not be found in the lymphoid organs. However, lymphocytes isolated from the tissue directly surrounding the subcutaneous SL2 tumor could arm macrophages in vitro.Shortly after subcutaneous tumor grafting cytotoxic macrophages were found in the peritoneal cavity. In the serum macrophage arming factors were detected that rendered macrophages cytotoxic in vitro. This cytotoxicity of the peritoneal macrophages and the presence of macrophage arming factors in the serum showed a similar biphasic pattern. The first phase of cytotoxicity between day 3 and 8 after tumor grafting was tumor (SL2) specific. The second phase from day 12 and onwards was not tumor specific. During the first 4 days after SL2 grafting the DBA/2 mice expressed a specific concomitant immunity to a second tumor graft. Then 7 or more days after grafting the first SL2 tumor, the concomitant immunity was nonspecific as the growth of a second SL2 tumor graft and a L5178Y (DBA/2) tumor graft were inhibited. In addition, the immune suppressive activity of serum and lymphocytes was tested. Neither serum nor lymphocytes from SL2-bearing mice suppressed the macrophage arming capacity of SL2 immune lymphocytes. Lymphocytes from tumor-bearing mice did not inhibit the capacity of SL2-immune lymphocytes to transfer resistance to naive animals. On the contrary, lymphocytes obtained from SL2-bearing mice 14 days after SL2 grafting transfered tumor resistance in a Winn-type assay. These data suggest that the growth of an antigenic tumor is due to the inability of the immune system to mount an effective antitumor effector cell population during tumor growth, rather than an immune suppression of the antitumor reactivity, as a limited immune reactivity could be detected in tumor-bearing mice, whereas immune suppression could not be detected.     

Effects of macrophage activity on the antibody-dependent cytotoxicity against Trichinella spiralis newborn larvae: an in vitro cytotoxicity and ultrastructural study

The effect of the activity of macrophages on the antibody-dependent cytotoxicity against Trichinella spiralis newborn larvae was studied in vitro. Macrophages present in peritoneal exudates from mice genetically selected for high and low antibody production (HL and LL, respectively) showed an inverse cytotoxic effect. Cells from HL mice were ineffective, whereas cells from LL mice had a very high killing capacity. Ultrastructural studies of cells after incubations of up to 36 h supported these observations. Furthermore, peritoneal macrophages from congenitally athymic (nu/nu) mice showed a higher killing potential than cells from thymus-bearing littermates (+/nu) mice. The activity of the latter cells could be increased by in vitro pretreatment of the mice with Calmette-Guérin bacillus, a well-known macrophage stimulating agent. The results indicate that macrophages, although not the only effector cells, may play an important role in the defence against T. spiralis newborn larvae.     

Infection of macrophages with Friend virus: relationship to the spontaneous regression of viral erythroleukemia.

Resident peritoneal macrophages from normal mice were refractory to infection with the RFV or conventional strains of Friend virus (FV). Stimulation of DNA synthesis in the macrophage population by induction of an exudate in vivo or treatment in vitro with macrophage colony-stimulating factor resulted in productive infection following exposure to virus. Similarly, normal resident macrophages did not become infected in vivo following transfer to leukemic mice, while exudate macrophages did become infected. Bone marrow macrophage stem cells were stimulated to replicate and mature in clonal agar cultures in the presence of colony-stimulating factor. These replicating stem cells could be infected with RFV, as shown by virus production in the resultant progeny macrophages. Transfer of normal resident peritoneal macrophages to leukemic progressor mice caused regression of the disease. In contrast, transfer of normal bone marrow cells was ineffective in causing leukemia regression. During erythroleukemogenesis induced by RFV, macrophage precursor cells in all of the mice became infected with virus. In mice with a progressive and lethal leukemia, mature end-stage macrophages were produced which were also infected with virus. In mice in which the leukemia would later spontaneously regress, the infected stem cells were eliminated and the marrow became repopulated with uninfected cells. The resultant progeny macrophages which appeared in the peritoneal cavity were uninfected and thus capable of participating in or causing leukemia regression.     

Characterization of the Growth Factor Activity of Amniotic Fluid on Cells from Hematopoietic and Lymphoid Organs of Different Life Stages

We investigated the proliferation-promoting effects of murine amniotic fluid (MAF) on in vitro cultured cells originally obtained from murine hematopoietic and lymphoid organs at different life stages. MAF promoted proliferation of the fetal liver cells (FLC), newborn spleen cells and adult bone marrow cells. The proliferation-promoting activity of MAF was extended to liver cells and spleen cells from mice younger than 2 weeks old. MAF did not, however, promote the proliferation of newborn or adult thymocytes, or of spleen cells, liver cells or peritoneal cells from 2-week-old or older mice. Rather, it partially inhibited the proliferation of spleen cells, thymocytes and peritoneal cells from 1-year-old mice. These results suggest that MAF contains growth factors for hematopoietic stem cells but not for either mature or immature T lymphocytes. Supporting this view, the MAF activity was partially neutralized by a polyclonal anti-mouse stem cell factor (SCF) antibody. Moreover, the immunoblotting of MAF against anti-mouse SCF antibody revealed a band at 30–32 kDa corresponding to the previously reported SCF. Interestingly, MAF was able to maintain FLC and adult bone marrow cells alive in culture for a relatively long time (2 weeks). The MAF activity was further shown to be partially and cell type-dependently antagonized by TNF-α and TGF-β. These results provided evidence that MAF contains potentially multiple growth factors preferentially affecting the early stage of hematopoiesis, one of which is SCF.     

Peri- and postnatal development of heterogeneity in the amounts of endoplasmic reticulum in mouse hepatocytes

The surface density and area per cell of the endoplasmic reticulum (ER) in periportal and perihepatic hepatocytes from male ddY mice, "17-, 18-, and 19-day-old fetuses," "newborn and 1-, 5-, 10-, and 20-day-old animals," and "adult animals" were analyzed by quantitative electron microscopy. The surface density of rough ER was not significantly different between periportal and perihepatic cells in all age groups examined, except for 19-day-old fetuses in which the value was greater in periportal cells than perihepatic cells. The surface density of smooth ER and total (rough and smooth) ER did not significantly differ between the periportal and perihepatic cells from 17-day-old fetuses to 5-day-old animals. In 10- and 20-day-old and adult animals, the values of smooth and total ER were greater in perihepatic cells than in periportal cells. When the data were expressed as area per cell, the patterns of subacinar distributions hardly differed, but age-related changes differed considerably from the patterns seen in the surface density data. The differences were generally caused by the increase in hepatocyte volume between 20 days of age and adulthood, especially in perihepatic cells, and by the changes in volume during the perinatal period. The results show that differences in the surface density and area per cell of smooth and total ER between periportal and perihepatic hepatocytes evident in adult animals are not present in fetal and newborn animals but arise during postnatal development.     

Immunocytochemical properties of stellate ganglion neurons during early postnatal development

Neurotransmitter features in sympathetic neurons are subject to change during development. To better understand the neuroplasticity of sympathetic neurons during early postnatal ontogenesis, this study was set up to immunocytochemically investigate the development of the catecholaminergic, cholinergic, and peptidergic phenotypes in the stellate ganglion of mice and rats. The present study was performed on Wistar rats and Swiss mice of different ages (newborn, 10-day-old, 20-day-old, 30-day-old, and 60-day-old). To this end, double labeling for tyrosine hydroxylase (TH), choline acetyltransferase (ChAT), vasoactive intestinal (poly)peptide (VIP), neuropeptide Y (NPY), galanin (GAL), and somatostatin (SOM) was applied. The results obtained indicate that the majority of the neurons in the stellate ganglion of both species were TH-positive from birth onward and that a large part of these neurons also contained NPY. The percentage of neurons containing TH and NPY invariably increased with age up to 60 days postnatally. A smaller portion of the stellate ganglion neurons contained other types of neuropeptides and showed a distinct chronological pattern. The proportion of VIP- and ChAT-positive neurons was maximal in 10-day-old animals and then decreased up to 60 days of age, whereas the number of SOM-positive cells in rats significantly decreased from birth onward. In newborn rats, VIP-, ChAT- and SOM-positive neurons were largely TH-positive, while their proportions decreased in 10-day-old and older rats. Accordingly, the largest part of VIP-positive neurons also expressed SOM immunoreactivity at birth, after which the number of neurons containing both peptides diminished. The VIP- and SOM-positive cells did not contain NPY in any of the age groups studied. In rats up to 10 days of life, GAL-immunoreactive (-IR) neurons were scarce, after which their number increased to reach a maximal value in 30-day-old animals and then declined again. The SOM-reactive cells had the smallest size in all rats, while the largest neurons were those containing ChAT. In the mouse stellate ganglion, VIP- and ChAT-IR neurons were larger in comparison to NPY- and TH-IR cells. Our study further revealed some species differences: compared to mice the proportion of neurons containing TH and NPY was higher in rats at all ages under study. Furthermore, no GAL-immunostained neurons were found in mice and the number of SOM-positive cells in mice was limited compared to that observed in rats. In conclusion, the development of neurotransmitter composition is complete in rats and mice by their second month of life. At this age, the percentages of immunopositive cells have become similar to those reported in adult animals.     

Intraperitoneal amyloid formation by amyloid enhancing factor--rich macrophages in ascitic fluid.

Although resident peritoneal cells from amyloidotic mice (amyloidotic peritoneal cells) are capable of processing the precursor protein of secondary amyloidosis, serum amyloid A (SAA) to amyloid fibrils, the peritoneum is a rare site for amyloid deposition. This is considered to be due to a deficiency of SAA in the peritoneum. To increase the supply of SAA to the peritoneum, ascitic fluid containing about the same protein constituents as in the serum was induced in mice. Amyloidotic peritoneal cells were packed in a microchamber which was shielded with filter membranes, and cultured in ascitic fluid supplemented with additional inflammatory factors. On the 7th day, Congo red-positive structures which showed green birefringence under polarized light were found inside and occasionally outside the chamber. By anti-AA or -SAA immunostaining, amyloid deposits and the cell surfaces of macrophages were positive. Immunologic depletion of T- and B-lymphocytes from the amyloidotic peritoneal cells did not adversely effect the amyloid formation in microchambers. These results suggest that either ascitic fluid containing sufficient amounts of SAA, or peritoneal macrophages with a high amyloid enhancing factor (AEF) activity are indispensable for AA amyloid fibrillogenesis in the peritoneum.     

Protective effect of recombinant human interleukin-2 against lethal infection caused by Klebsiella pneumoniae

The effects of recombinant human interleukin-2 (rIL-2) administered prophylactically on the death of CBA/J mice challenged with Klebsiella pneumoniae 27 intraperitoneally were examined. rIL-2 administered subcutaneously at 20 micrograms per mouse for 7 days enhanced survival after a lethal challenge. The injection of anti-asialo GM1 antibody did not influence the effect of rIL-2. In mice given rIL-2, the number of peritoneal macrophages increased, and the infiltration of polymorphonuclear leukocytes (PMN) into the peritoneal cavity after the bacterial challenge was enhanced. In addition, adoptive transfer of sera and peritoneal exudate cells (PEC), consisting of an approximately equal number of macrophages and PMN, obtained from mice given rIL-2 enhanced resistance to a K. pneumoniae infection, compared with adoptive transfer of sera and PEC obtained from mice not given rIL-2. These results indicate that rIL-2 protects mice from a lethal challenge with K. pneumoniae, and suggest that the protective effect is due to an increase in the number of phagocytic cells and in the cooperative activity of the sera and the phagocytic cells.     

Contribution to histochemical distribution of non-specific cholinesterase activity in sensory ganglia of some mammals

The activity of non-specific cholinesterase was demonstrated histochemically in satellite cells of the spinal ganglia from adult rat, cat, rabbit and baboon. The spinal ganglia of newborn rats displayed distinct intraneuronal reactivity for non-specific cholinesterase while a low reactivity was observed in satellite cells. The spinal and trigeminal ganglia of adult mice contained satellite cells with non-specific cholinesterase reactivity only sporadically. Most of reaction product for non-specific cholinesterase activity (from low to high intensity) was found in perikarya of the neurons. Spinal and trigeminal ganglia of the same mice embryo exhibited diffuse staining for non-specific cholinesterase activity remaining in the spinal ganglia of newborn mice. The trigeminal ganglia of newborn mice exhibited, however, more differentiated pattern of the positive reaction for non-specific cholinesterase like adult animals. The pattern of histochemical distribution of non-specific cholinesterase activity in trigeminal and spinal ganglia from mice of various ages corresponds with morphological differentiation and maturation undergoing in a rostrocaudal wave. Intraneuronal presence of non-specific cholinesterase activity in sensory ganglia during development and in adult animals gives a new possibilities for explanation of the functional involvement of this enzyme in the nervous system.     

Macrophages as effector cells of protective immunity in murine schistosomiasis

Mice infected with Schistosoma mansoni develop a dramatic (five- to eightfold) increase in numbers of peritoneal leukocytes, and approximately 65% of these cells are macrophages. By several biochemical and cytochemical criteria, these cells were comparable to resident peritoneal macrophages of normal mice. However, macrophages from schistosome-infected mice exhibited significant nonspecific tumoricidal activity in vitro, a function associated with immunologically activated cells. The time course for development of activated macrophages in the peritoneal cavity was dependent upon the route of infection. Cytotoxic cells were present in the peritoneal cavity by 3 weeks after intraperitoneal infection, but were not evident until several weeks later in animals infected percutaneously, subcutaneously, or intravenously. However, by 3 weeks after subcutaneous infection, tumoricidal macrophages appeared in the peritoneal cavity after intraperitoneal challenge with soluble schistosome antigens. Macrophage activation was independent of the development of egg granulomas, since tumoricidal cells could be found prior to the onset of egg production and were also present in mice infected with only male worms. Development of activated macrophages in these instances is thus consistent with previous observations on induction of T lymphocyte reactivity toward schistosomula. Since other manipulations known to activate macrophages have been shown to induce partial resistance to schistosome infection, the finding that macrophage activation results from primary S. mansoni infection itself suggests that these cells may play a major role in acquired immunity to this parasite.     

Evidence for granulocyte-mediated macrophage activation after C. parvum immunization

It has been previously demonstrated that at the peak of the peritoneal response to Corynebacterium parvum (Day 4), cytolytic macrophages can be characterized by the presence of intracellular bacteria. In the present study, the role of neutrophils in the activation of peritoneal macrophages by C. parvum was investigated. Inflammatory neutrophils isolated 5 hr after ip administration of C. parvum were transferred to normal, syngeneic mice and the peritoneal macrophages of recipients harvested 4 days later were tested for cytoxicity against HeLa cells. Neutrophils isolated from mice 5 hr after C. parvum immunization were effective in inducing cytolytic macrophages. Less than 100-fold as much bacteria was needed to induce comparable levels of cytotoxic activity when introduced inside granulocytes. Neutrophils obtained from mice 48 hr after C. parvum injection or mononuclear cells were not good macrophage activators. Viable neutrophils were not required as freeze-thawed cells were able to activate macrophages in recipient mice. The intracellular distribution of C. parvum changed dramatically with time. Initially almost all bacteria were found within neutrophils. By 24 hr, many macrophages contained either bacteria or granulocytes which had ingested C. parvum. Pyridine extracts of C. parvum, which do not activate peritoneal macrophages when injected directly into mice, did not induce neutrophils capable of activating macrophages. The residue of pyridine-extracted C. parvum did induce neutrophils that could activate macrophages when transferred. The results suggest that processing of the bacteria by inflammatory granulocytes may be an obligatory step in macrophage activation by this agent. The peak response occurred earlier than T-cell immunity is usually observed and it is suggested that direct activation of macrophages via ingestion of neutrophils may represent the earliest stage of macrophage activation by C. parvum.     

Protective effect of acidic mannan fraction of bakers' yeast on experimental candidiasis in mice

An acidic fraction of bakers' yeast mannan, WAM025, showed a significant protective effect against Candida albicans infection in mice, but a neutral fraction of the same bakers' yeast mannan, WNM, did not exhibit this effect. Moreover, pretreatment with WAM025 resulted in a marked reduction of proliferation of C. albicans cells in the organs of the infected mice. We investigated the stimulative effect of these mannan fractions on the function of mouse peritoneal phagocytes, and found that mice administered WAM025 showed a greater increase in the number of peritoneal exudate cells, macrophages and polymorphonuclear leucocytes (PMN), than the mice treated with WNM, especially in the proportion of PMN. Peritoneal phagocytes, PMN and macrophages obtained from WAM025-treated mice showed marked candidacidal activity. Of the phagocytes, PMN were responsible for the larger part of the candidacidal activity. The myeloperoxidase activities of PMN and macrophages in WAM025-treated PEC were greater than in untreated macrophages. The myeloperoxidase activity of WAM025-treated PMN was significantly greater than that of WAM025-treated macrophages. This activity paralleled the active oxygen-releasing activity of the phagocytes. On the other hand, the phagocytic activity of phagocytes from mice administered WNM or WAM025 for C. albicans cells was identical to that of untreated phagocytes. WAM025 seems to cause enhance elimination of the pathogen from mice, by increasing the number and candidacidal activity of phagocytic cells.     

Enhanced accumulation of inflammatory neutrophils and macrophages mediated by transfer of T cells from mice immunized with Listeria monocytogenes

We have previously shown that listeria-immunized mice recruit more inflammatory neutrophils and macrophages to the peritoneal cavity after i.p. injection of a sterile irritant than do nonimmune mice. Because the inflammatory phagocytes that were obtained from listeria-immune and nonimmune mice did not differ in their ability to kill Listeria monocytogenes in vitro, this suggested that the rapid recruitment of listericidal inflammatory neutrophils and macrophages may be critically important for resistance to listeriosis. In this study we demonstrate that the transfer of listeria-immune T cells, which enhances recipient resistance to listeriosis, also increases the ability of recipients to mobilize inflammatory neutrophils and macrophages to the peritoneal cavity after the i.p. injection of dead listeria. The transfer of enhanced inflammatory responsiveness was blocked by pretreatment of the transferred cells with anti-Thy-1.2 plus complement, and the magnitude of the inflammatory cell accumulation was dependent on the number of listeria-immune T cells that were injected. Inflammatory neutrophils and macrophages that were obtained from the mice after the transfer of listeria-immune or nonimmune T cells (plus dead listeria) did not differ in their ability to kill L. monocytogenes in vitro. These data suggest that the elicitation of an inflammatory response may be an important event in T cell-mediated resistance to listeriosis.     

Appearance of a Cell Surface Antigen Associated with the Activation of Peritoneal Macrophages in Mice

A relatively large population of murine peritoneal exudate macrophages induced with viable BCG or heat-killed Corynebacterium parvum was stained by the antiserum prepared against purified gangliotetraosyl ceramide (asialo GM1), while only a small population of peritoneal resident macrophages or peritoneal exudate macrophages induced with proteose peptone was stained. The cytotoxicity assay of those macrophages with anti-asialo GM1 plus complement supported these results. Peritoneal macrophages induced with BCG or C. parvum showed strong cytotoxicity for EL4 cells in vitro, while resident or peptone-induced peritoneal macrophages showed no cytotoxicity. BCG- or C. parvum-induced peritoneal cells contained both NK cells and cytotoxic macrophages, and either in vivo or in vitro pretreatment of the cells with anti-asialo GM1 and complement abolished the activities of both types of cells. Peptone-induced peritoneal macrophages incubated with lymphokines (LK) or lipopolysaccharide (LPS) were cytotoxic for EL4 cells and contained an increased number of cells stained by anti-asialo GM1. The cytotoxicity of these in vitro activated macrophages was reduced by treatment with anti-asialo GM1 plus complement. When peptone-induced peritoneal macrophages were incubated with LK, the number of cells stained by anti-Ia antiserum increased, but the number did not increase when the macrophages were incubated with LPS. Pretreatment of peptone-induced macrophages with anti-asialo GM1 plus complement did not affect the ability of the macrophages to be activated by LK. These results taken together strongly suggest that the antigen (s) reactive with anti-asialo GM1 is expressed on the cell surface of cytotoxic peritoneal macrophages in mice.     

Orungo virus: organ distribution with histopathology and development of experimentally infected Swiss albino mice

The organ distribution and pathogenecity of Orungo virus were studied in Swiss Albino mice following intracerebral and intraperitoneal inoculations. There was an age-related response in mice to Orungo virus ic infection. Virus multiplied to higher titres in the brain of newborn (2-day-old) mice than in the other organs. The histopathologic changes which were restricted to the brain included diffuse mononuclear cell infiltration, prominent perivascular and interstitial oedema in the cerebrum and cerebellum. In 10-day-old mice, low level infective virus was detected only in the brain, with resultant mild and focal mononuclear cell infiltration in the cerebral cortex. Recovery from Orungo virus ic infection in 10-day-old animals is accompanied by stunted growth. Orungo virus did not multiply in 21-day-old mice which were found to be histologically unremarkable. Following ip inoculation Orungo virus did not multiply, nor was there an histopathological change in inoculated newborn, 10-day or 21-day-old mice.     

Response of resident murine peritoneal macrophages to in vivo administration of granulocyte-macrophage colony-stimulating factor

The effect of s.c. inoculation of purified recombinant derived granulocyte-macrophage (GM)-CSF on resident murine peritoneal macrophages was assessed in this study. From 18 to 24 h after s.c. administration of GM-CSF to normal mice, the resident peritoneal macrophages were harvested and the levels of membrane-bound IL-1, FcR, Mac-1 cell-surface Ag, and class II MHC expression were assessed. Peritoneal cells from GM-CSF-inoculated mice had significantly greater levels of membrane-bound IL-1 than did control mice. In addition when resident peritoneal macrophages from normal mice were purified by adherence and grown in the presence of GM-CSF, they produced greater levels of both membrane-bound and secreted IL-1. The peritoneal cells from GM-CSF-inoculated mice did not differ from controls in the expression of class II MHC-encoded Ag. This observation was confirmed by the finding that GM-CSF was unable to induce class II MHC expression on P388D1 cells, whereas a secondary mixed leukocyte culture supernatant was. Peritoneal cells from GM-CSF-inoculated mice also exhibited greater levels of expression of FcR and the Mac-1 cell-surface Ag. This resulted in an increase in their ability to phagocytose opsonized SRBC in vitro.