Effects of long‐distance running on serum opsonic activity measured by chemiluminescence

Exhaustive exercise such as long‐distance running has been shown to increase susceptibility to infection. In order to investigate whether serum opsonic activity plays a role in such conditions, we utilized luminol‐dependent and lucigenin‐dependent chemiluminescence (LmCL and LgCL). We took serum samples from 24 male marathon runners before and after running 30 km. Neutrophils were isolated from the peripheral blood of healthy volunteers. Serum opsonic activity was examined by measuring neutrophil ROS stimulated with zymosan particles opsonized by the serum samples. Immunoglobulin and complement levels in the serum were also measured. After a 30 km run, the maximum light emission was increased and the time to reach the maximum light emission was shortened significantly (p < 0.05) in LmCL. However, there were no significant changes in the immunoglobulin and complement levels. The increase of ROS production may suggest that serum opsonic activity is accelerated after running 30 km. Thus, serum opsonic activity might not play a significant role in the susceptibility to infection after long‐distance running. Copyright © 2003 John Wiley & Sons, Ltd.     

Schizophyllan (SPG)-treated macrophages and anti-tumor activities against syngeneic and allogeneic tumor cells

We tested anti-tumor activities of macrophages treated with a neutral polysaccharide, schizophyllan (SPG), against syngeneic and allogeneic tumor cell lines. SPG was a macrophage stimulant which was not mitogenic to lymphocytes. That made a sharp contrast with the data that Corynebacterium parvum, BCG, and muramyl dipeptide (MDF) were macrophage stimulants which had lymphocyte-activating properties. Treatment of SPG-treated PEC with Thy12 monoclonal antibody and guinea pig complement did not affect the capabilities of tumor-cell-growth suppression by the treated PEC. Thus, the effector cells were peritoneal adherent cells (macrophages morphologically) and effector-to-target contact seemed to be necessary for effective tumor-cell-growth inhibition, although contradictory data exist for this. Murine peritoneal adherent cells harvested 4 days after a single IP injection of SPG at a dose of 100 mg/kg body weight of mouse showed the most prominent cytostatic and cytotoxic activities against syngeneic and allogeneic tumor cells. The distribution of anti-tumor activity in macrophages of various sizes followed the same pattern as macrophages treated with C. Parvum, i.e., larger macrophages showed more remarkable anti-tumor activity. Crude nonadherent peritoneal cells incubated with SPG at a concentration of 10 micrograms/ml, 100 micrograms/ml, or 1 mg/ml did not secrete lymphokine that rendered macrophages cytotoxic, while ConA-treated nonadherent cells did so. Furthermore, spleen cells treated with SPG in vivo did not secrete macrophage-activating lymphokine in the presence of SPG. On the other hand, addition of 1 mg/ml of SPG-treated peritoneal adherent cells and bone-marrow-derived macrophages in vitro rendered them cytotoxic to a moderate degree. This implies that SPG may activate macrophages directly, allowing them to become cytotoxic in the peritoneal cavity. Lastly, SPG could induce production of II-1-like factor to a moderate degree. SPG, whose molecular structure is well elucidated, will provide us with a strong tool to analyze the mechanism of macrophage activation both in vitro and in vivo.     

The relationship between exhaled carbon monoxide and human neutrophil function in the Japanese general population

We have evaluated the relationship between exhaled carbon monoxide (CO) level and neutrophil‐related functions such as reactive oxygen species (ROS) production capability, phagocytic activity and serum opsonic activity in the general population. Serum opsonic activity was determined by measuring the effects of serum on neutrophil ROS production capability using lucigenin‐ and luminol‐dependent chemiluminescence (LgCL, LmCL). LgCL is associated with the detection of O₂^?, whereas LmCL mainly detects H₂O₂ and HOCl, which are higher reactive oxygen radicals. In females, exhaled CO level was found to have positive associations with ROS production capability and LgCL. However, the opposite tendency was seen between exhaled CO level and LmCL in both genders. This result suggests that neutrophil ROS production in females may have contributed to oxidative stress, which led to the increases in intrinsic CO and exhaled CO consequently. Such changes then may have inhibited the process of changing reactive oxygen radicals into higher oxidizing potential levels. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of the histiophagous ciliate Philasterides dicentrarchi on turbot phagocyte responses

Philasterides dicentrarchi is an opportunistic histiophagous ciliate parasite causing systemic scuticociliatosis in cultured turbot (Scophthalmus maximus L.). This study investigated the effects of inoculation with live or killed trophozoites of this ciliate (plus 3% thioglycollate) on the in vitro phagocytic activity and respiratory-burst responses of inflammatory peritoneal leucocytes obtained from the fish thus treated. The phagocytic activity of leucocytes from fish inoculated with killed P. dicentrarchi was higher in the presence than in the absence of infected turbot serum (ITS). The effect of ITS was smaller in fish inoculated with live P. dicentrarchi, indicating modulation of the opsonic activity of ITS. Inoculation with live ciliates led to a significant increase in subsequent in vitro extracellular ROS production, but only when normal turbot serum (NTS) or ITS was included in the assay medium. Inclusion of live P. dicentrarchi in the medium abolished this increase, suggesting ROS-scavenging activity. Inoculation with live P. dicentrarchi led to a significant decline in subsequent in vitro intracellular ROS production; when NTS was included in the medium, there was a significant increase in intracellular ROS production, but no such increase was observed when ITS was included in the medium. Inoculation with live P. dicentrarchi alone did not increase subsequent in vitro NO? production in response to LPS; a significant increase was observed when NTS or ITS was included in the assay medium, but this increase was not affected by prior inoculation with P. dicentrarchi. These results suggest that the amphizoic nature of this parasite may reflect the ease with which it can develop mechanisms of evasion of the host immune response.     

The Relationship Between Serum Selenium Concentration and Neutrophil Function in Peripheral Blood

We evaluated the relationships between neutrophil-related functions and serum selenium (Se) concentration in the general population. We examined 800 subjects who had participated in the Iwaki Health Promotion Project in 2005 to determine the relationships between serum Se concentration and neutrophil-related functions such as the production capability of reactive oxygen species (ROS), phagocytic activity, and serum opsonic activity (SOA). In nonstimulated neutrophils, i.e., in neutrophils at their baseline condition before the application of the phagocytic stimulus, the serum Se concentration tends to be high and the ROS production tends to be low. With regard to SOA, there was a significant negative correlation between lucigenin-dependent chemiluminescence and serum Se concentration in both men and women. Moreover, in women, a significant negative correlation was observed between luminol-dependent chemiluminescence and serum Se concentration. These results suggest that subjects with a lower serum Se concentration may be exposed to a greater chronic oxidative stress due to neutrophil ROS production. In addition, the findings of our study suggest that women rather than men benefit more from Se against oxidative stress.     

Schizophyllan (SPG)-treated macrophages and anti-tumor activities against syngeneic and allogeneic tumor cells

Summary We tested anti-tumor activities of macrophages treated with a neutral polysaccharide, schizophyllan (SPG), against syngeneic and allogeneic tumor cell lines. SPG was a macrophage stimulant which was not mitogenic to lymphocytes. That made a sharp contrast with the data that Corynebacterium parvum, BCG, and muramyl dipeptide (MDF) were macrophage stimulants which had lymphocyte-activating properties. Treatment of SPG-treated PEC with Thy12 monoclonal antibody and guinea pig complement did not affect the capabilities of tumor-cell-growth suppression by the treated PEC. Thus, the effector cells were peritoneal adherent cells (macrophages morphologically) and effector-to-target contact seemed to be necessary for effective tumor-cell-growth inhibition, although contradictory data exist for this. Murine peritoneal adherent cells harvested 4 days after a single IP injection of SPG at a dose of 100 mg/kg body weight of mouse showed the most prominent cytostatic and cytotoxic activities against syngeneic and allogeneic tumor cells. The distribution of anti-tumor activity in macrophages of various sizes followed the same pattern as macrophages treated with C. Parvum, i.e., larger macrophages showed more remarkable anti-tumor activity. Crude nonadherent peritoneal cells incubated with SPG at a concentration of 10 g/ml, 100 g/ml, or 1 mg/ml did not secrete lymphokine that rendered macrophages cytotoxic, while ConA-treated nonadherent cells did so. Furthermore, spleen cells treated with SPG in vivo did not secrete macrophage-activating lymphokine in the presence of SPG. On the other hand, addition of 1 mg/ml of SPG-treated peritoneal adherent cells and bone-marrow-derived macrophages in vitro rendered them cytotoxic to a moderate degree. This implies that SPG may activate macrophages directly, allowing them to become cytotoxic in the peritoneal cavity. Lastly, SPG could induce production of II-1-like factor to a moderate degree. SPG, whose molecular structure is well elucidated, will provide us with a strong tool to analyze the mechanism of macrophage activation both in vitro and in vivo.Abbreviations PEC peritoneal exudate cells - SPG schizophyllan - LPS lipopolysaccharide - Con A concanavalin A - CGN carrageenan - B. M. bone marrow - FCS fetal calf serum - BCG bacille Calmétte Guérin - Il-1 interleukin 1 - PPD pure protein derivatives - MDP muramyl dipeptide - C. parvum Corynebacerium parvum Dr. Sugawara is a Research Fellow of the Alberta Heritage Foundation for Medical ResearchDr. Lee is a Research Associate of the National Cancer Institute of Canada     

Immunomodulatory activity of Bengkoang (Pachyrhizus erosus) fiber extract in vitro and in vivo

Bengkoang (Pachyrhizus erosus (L.) Urban) is one of the most popular edible root vegetables in Indonesia. Bengkoang contains fairly large amounts of carbohydrates and crude fiber. The purpose of this research is to evaluate the immunomodulatory effect of the bengkoang fiber extract (BFE) in vitro and in vivo. BFE was prepared by heating the powder of bengkoang fiber suspended in distilled water at 121 °C for 20 min. BFE facilitated IgM production by the human hybridoma cell line HB4C5 cells. In addition, production of IgM, IgG, and IgA by mouse primary splenocytes was facilitated by BFE in a dose-dependent manner. BFE also significantly facilitated production of both interleukin-5 and interleukin-10 by splenocytes. Immunoglobulin production by lymphocytes from the spleen, Peyer’s patch, and mesenteric lymph node were significantly activated by oral administration of BFE to mice for 14 days. The serum immunoglobulin levels of IgG, IgM, and IgA were also significantly enhanced. Furthermore, cytokine production by lymphocytes from the spleen, Peyer’s patch, and mesenteric lymph node were also facilitated by oral administration of BFE. These results suggest that BFE has positive effects on the immune system in vitro and in vivo.     

Effect of Tetramicra brevifilum (Microspora) infection on respiratory-burst responses of turbot (Scophthalmus maximus L.) phagocytes

In vitro assays were performed to investigate microsporidian-induced intracellular and extracellular production of reactive oxygen species (ROS) by peritoneal-exudate adherent (PEA) cells from turbot. ROS production was quantified using the fluorescent reagents OxyBURST Green H2HFF BSA (extracellular) and OxyBURST Green H2DCFDA succinimidyl ester (intracellular). Five days before assay, the cells had been elicited in vivo by intraperitoneal injection of sodium thioglycollate or spores of Tetramicra brevifilum. Elicitation with spores led to a marked increase in the proportion of neutrophils among PEA cells. PEA cells from normal turbot showed considerable extracellular and intracellular ROS production in response to microsporidian spores. By contrast, PEA cells from microsporidian-infected turbot showed considerably reduced extracellular and intracellular ROS production in response to microsporidian spores. Extracellular ROS production was affected by the addition of infected turbot serum to the assay medium, regardless of whether the PEA cells had been obtained from normal or infected fish. The presence of microsporidian-infected turbot serum significantly reduced intracellular ROS production by PEA cells elicited with microsporidian spores. These results suggest that (a) microsporidian spores partially suppress the repiratory-burst response of turbot phagocytes; and (b) infected turbot serum contains substances capable of modulating the respiratory-burst response of turbot phagocytes to microsporidian spores.     

Effect of opsonization on oxidative metabolism of plaice (Pleuronectes platessa L.) neutrophils

The effect of serum opsonization on Vibrio alginolyticus (heat-killed)-stimulated chemiluminescence (CL) by plaice kidney- and peritoneal exudate-derived neutrophils was investigated. Peritoneal neutrophils only recognized heat-labile and kidney neutrophils only heat-stable opsonic activity in normal serum. Specific antibody did not show opsonic activity nor any synergism with the normal serum opsonins for either neutrophil population. Evidence was found for the production, by plaice neutrophils, of H2O2, O2-, OH. and two or more, as yet unidentified, reactive oxygen species (ROS).     

The effect of (1-->3)-beta-D-glucans, carboxymethylglucan and schizophyllan on human leukocytes in vitro

(1-->3)-beta-D-glucans are known as potent inductors of humoral and cell-mediated immunity in humans and animals. (1-->3)-beta-D-glucans isolated from various sources differ in their chemical structure and physical parameters and consequently in their immunomodulatory potential. In this study the immunomodulatory activity of two (1-->3)-beta-D-glucans schizophyllan (SPG) and carboxymethylglucan (CMG) was determined and compared on human blood leukocytes in vitro. Both SPG and CMG activated blood phagocytes and lymphocytes as demonstrated by increased whole blood production of reactive oxygen species, by increased production of pro-inflammatory cytokines IL-6, IL-8, and TNF-alpha, by increased surface expression of CD69 on lymphocytes, and by altered expression of CD11b and CD62L on polymorphonuclear leukocytes and monocytes. SPG demonstrated a significantly higher potential to stimulate blood phagocytes and production of selected pro-inflammatory cytokines than CMG. The higher potency of SPG to stimulate human blood phagocytes in vitro could be caused by factors such as higher branching frequencies or neutral polymer charge of SPG or different conformation in solution if compared with CMG.     

Unconjugated bilirubin inhibits VCAM-1-mediated transendothelial leukocyte migration

During lymphocyte migration, engagement of VCAM-1 stimulates the generation of endothelial cell-derived reactive oxygen species (ROS) and activation of matrix metalloproteinases, facilitating endothelial retraction. Because bilirubin is a potent antioxidant, we examined the hypothesis that this bile pigment inhibits VCAM-1-dependent cellular events. The migration of isolated murine splenic lymphocytes across monolayers of murine endothelial cell lines (which constitutively express VCAM-1) is significantly inhibited by physiological concentrations of bilirubin, in the absence of an effect on lymphocyte adhesion. Bilirubin administration also suppresses VCAM-1-stimulated ROS generation and reduces endothelial cell matrix metalloproteinase activity. In a murine asthma model characterized by VCAM-1-dependent airway inflammation, treatment of C57BL6/J mice with i.p. bilirubin decreases the total leukocyte count in the lung parenchyma and lavage fluid, through specific inhibition of eosinophil and lymphocyte infiltration. Blood eosinophil counts were increased in bilirubin-treated animals, while VCAM-1 expression in the capillary endothelium and cytokine levels in both lung lavage and supernatants from cultured lymph node lymphocytes were unchanged, suggesting that bilirubin inhibits leukocyte migration. Conclusion: bilirubin blocks VCAM-1-dependent lymphocyte migration in vitro and ameliorates VCAM-1-mediated airway inflammation in vivo, apparently through the suppression of cellular ROS production. These findings support a potential role for bilirubin as an endogenous immunomodulatory agent.     

Gonadotropin-releasing hormone alters the T helper cytokine balance in the pregnant rat

The interactions between immune-endocrine and reproductive systems are heightened during pregnancy as an adaptive mechanism, and are regulated by a complex array of hormones and cytokines that control the survival of a semiallogeneic conceptus. GnRH can exert direct effects on the immune system via its receptor (GnRH-R) on lymphoid cells. In the present study, we employed in vitro, ex vivo, and in vivo approaches to investigate the role of GnRH in the modulation of T helper cytokines in pregnant rats undergoing termination of pregnancy. Day 8 pregnant rats were infused with a GnRH agonist (GnRH-Ag) for 24 h using an osmotic minipump. Sham control rats were infused with the vehicle, saline. Lymphocytes were isolated from sham and treated rats and polyclonally stimulated with immobilized anti-CD3 antibody. The levels of the signature T helper 1 (Th-1) cytokines (interferon-gamma [IFN-gamma] and interleukin-2 [IL-2]) and Th-2 cytokines (IL-4 and IL-10) were measured in culture supernatants. Using immunoflourescence confocal microscopy, we demonstrated for the first time the spatial localization of GnRH-R protein on the surface of lymphocytes. We observed a marked increase in IFN-gamma and inhibition of IL-4 production from lymphocytes of pregnant rats treated in vitro with different doses of GnRH-Ag. Further, the responsiveness of lymphocytes to produce IFN-gamma was markedly increased in cells cultured ex vivo from GnRH-Ag infused rats, whereas the capacity of lymphocytes to produce IL-4 was significantly inhibited. In addition, GnRH-Ag infusion in pregnant rats induced a shift toward Th-1 cytokines in the serum. We did not observe any significant difference in IL-2 and IL-10 production in response to GnRH-Ag. Our results suggest an additional function for GnRH as a Th-1 inducer and Th-2 inhibitor. GnRH can thus skew the cytokine balance to predominantly Th-1 type in pregnancy, leading to the termination of pregnancy in rats.     

Effect of 6 months' training on the reactive oxygen species production capacity of neutrophils and serum opsonic activity in judoists.

The effects of long-term training on the production of reactive oxygen species (ROS) from neutrophils and serum opsonic activity (SOA) remain to date unknown. The aim of this study was to evaluate the effect of 6 months training on ROS production and SOA in judoists. Fifty-six judoists were enrolled this study. White blood cell counts, serum creatine kinase (CK), asparate aminotransferase (ASAT), alanine aminotransferase (ALAT), lactate dehydrogenase (LDH) and ROS production from neutrophils, and serum opsonic activity (SOA) using the lucigenin and luminol probes, were measured before and after daily judo exercise (2 h) in March and September. The subjects started their training from March after no exercise for three months, and continued it for 6 months (until September). In March, myogenic enzymes such as CK, ASAT, LDH and neutrophil counts increased and immunoglobulins, complements and SOA decreased after daily judo exercise. Such significant changes were not seen in September. On the other hand, ROS significantly increased after daily judo exercise in both March and September, with no significant difference in the rates of change. In conclusion, 6 month training minimized the changes in SOA as well as muscle enzymes, neutrophil counts, serum immunoglobulins and complements. This could be categorized as a long-term training effect. However, no such change was seen in ROS.     

Human natural killer cytotoxic factor (NKCF): role of IFN-alpha

The relationship between production of NKCF and IFN-alpha by human lymphocytes was studied. NKCF activity was generated in response to K562-inducer cells. The presence of NKCF in supernatants was always accompanied by antiviral activity, but in several experiments IFN was detected without concomitant NKCF. In no instance was NKCF activity detected in the absence of IFN. Cell lines which were good inducers of IFN-alpha were found to be good inducers of NKCF. NKCF activity of supernatants was completely adsorbed after incubation with MOLT-4 cells, whereas there was only minimal depletion of IFN-alpha activity. Most of the antiviral activity and all of the NKCF activity of preformed supernatants was neutralized by anti-IFN-alpha serum, whereas anti-IFN-gamma serum and pH2 inactivation had minimal effect on either activity. Addition of IFN-alpha to neutralized supernatants restored NKCF activity. These experiments support the hypothesis that IFN-alpha is involved in the modulation of NKCF-lytic activity. Both antiviral and NKCF activities were abrogated when anti-IFN-alpha serum was added to cultures of lymphocytes plus inducer cells (induction phase). The addition of purified IFN-alpha to such cultures was effective in allowing resumption of NKCF activity; however, addition of IFN-gamma to these cultures did not overcome this block. The addition of purified IFN-alpha directly to supernatants generated in the presence of anti-IFN-alpha serum could not restore their NKCF activity, thereby suggesting an additional requirement for IFN-alpha in the production of NKCF. The possible role of IFN-alpha in the generation of NKCF and expression of its lytic activity is discussed.     

The effects of a two‐hour judo training session on the neutrophil immune functions in university judoists

The present study examined the effects of judo training on neutrophil and related functions. We measured and studied changes in the neutrophil and its related functions in 22 male university judoists immediately before (Pre values) and immediately after (Post values) a 2 h training session: reactive oxygen species (ROS) production capability, phagocytic activities (PA) and serum opsonic activity (SOA). Neutrophil count in whole blood, myogenic enzymes (creatine kinase, lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase), immunoglobulins (IgG, IgA and IgM) and complements (C3 and C4) in serum were also measured. The Post values of the neutrophil count, myogenic enzymes and IgG increased significantly compared with the Pre values. ROS production capability and SOA also significantly increased following training, although PA showed a slight decrease (but not statistically significant). Taking the findings of our previous studies into consideration, three major neutrophil or related functions, namely ROS production capability, PA and SOA, might compensate for each other to maintain the overall integrity of the neutrophil immune function, in that ROS and SOA increased to compensate for the slight decrease in PA, or PA slightly decreased to compensate for the increase in ROA and SOA after exercise. Copyright © 2008 John Wiley & Sons, Ltd.     

Effect of alcohol drinking and cigarette smoking on neutrophil functions in adults

In recent years, the effects of smoking and excessive alcohol consumption on immune function have been studied, due to a high prevalence of infection or cancer in heavy drinkers, and the combination of smoking and drinking was considered to be a carcinogenic risk. However, the effect of smoking and drinking on systemic immune function has yet to be clearly understood. In this study, we investigated neutrophil functions (reactive oxygen species (ROS) productive activity, phagocytic ability and serum opsonic activity) and their relationship with alcohol consumption or amount of smoking. In total there were 731 male and female adult subjects who participated in the Iwaki Health Promotion Project in 2005. Multiple regression analysis showed a trend of increased ROS production in male subjects and a statistically significant decrease was observed in phagocytic activity caused by smoking in female subjects. In other words, oxidative stress caused by smoking in male subjects may be involved in ROS production from neutrophils. Decreased phagocytic activity of neutrophils caused by smoking suggests that host defense functions were impaired in female subjects. A relationship between neutrophil functions and the amount of alcohol consumption was not observed. Copyright © 2011 John Wiley & Sons, Ltd.     

Proliferation of Toxoplasma gondii in inflammatory macrophages in vivo is associated with diminished oxygen radical production in the host cell

While reactive oxygen species (ROS) can kill Toxoplasma gondii in vitro the role these molecules play in vivo is not known. We used a flow cytometry-based assay to investigate the relationship between intracellular infection and ROS production during acute peritoneal toxoplasmosis in mice. A distinct population of ROS(+) inflammatory macrophages, detected by the oxidation of hydroethidine, was observed to increase progressively in frequency during the course of infection, and to be inversely correlated with the degree of cell parasitization. These data imply that either intracellular parasites inhibit ROS synthesis or, alternatively, ROS-producing cells contain anti-Toxoplasma activity. The latter interpretation was supported by the finding that uninfected ROS-producing inflammatory macrophages were resistant to infection in vivo. However, in the same animals, ROS-producing macrophages that had previously been parasitized could readily be infected with additional parasites, suggesting that the difference in ROS production between highly infected and less infected cells was not due to ROS-associated killing of parasites within these cells. In addition, macrophages infected with T. gondii in vitro and then briefly transferred to acutely infected mice upregulated ROS production in a manner that was again inversely correlated with the degree of intracellular parasitization. Taken together, these findings suggest that both ROS-associated anti-Toxoplasma activity and parasite-driven inhibition of ROS production underlie the observed pattern of ROS production. ROS function and parasite evasion of this function may contribute significantly to the balance between host defense and disease progression during acute infection.     

Regulation of primary spermatogonial proliferation in the frog (Rana esculenta): an experimental analysis

In order to study the regulation of primary spermatogonial (SPG) proliferation in the frog ( Rana esculenta ), mitotic and labelling indices of these cells were analysed, in vivo and in vitro , under different experimental conditions and periods of the year. Hypophysectomy, irrespective of the period of the year and independent of temperature, showed a remarkable negative influence on the mitotic or labelling index of the primary SPG. Replacement therapy with homologous pars distalis homogenate stimulated the proliferative activity, the stimulation being of significantly greater magnitude at 18°C than at 4°C. In parallel, mitotic index in vitro , in different periods of the year, after a 24-h incubation, was significantly higher at 20°C than at 8°C. At 2°C no 3H-thymidine labelling of the primary SPG was observed. Primary SPG labelling index in vitro increased with temperature, reaching the highest value at 15°C; it was, however, very low at 28°C. Under in vitro conditions FSH and LH stimulated primary SPG proliferation only when given together, but in vivo hypophysectomy stimulated SPG proliferation independently; GnRHa, thyroxine and prolactin were strongly stimulatory. The present in vitro data confirmed that testosterone acts synergistically with FSH-like substances to influence SPG proliferation. Unilateral castration rapidly increased the labelling index of the primary SPG in the remaining testis and this increased proliferative activity is assumed to be responsible for increased spermatogenetic activity and augmentation of testis mass later in time. It is suggested that temperature represents the constraint which controls the primary SPG responsiveness to hormonal factors.     

A T cell activity that enhances polyclonal IgE production and its inhibition by interferon-gamma

The addition of concanavalin A-stimulated supernatants of the helper T cell clone, D9.1, to cultures of lipopolysaccharide (LPS)-stimulated T-depleted mouse spleen cells caused more than a 100-fold increase in immunoglobulin (Ig) E production. These supernatants cause a 10-fold to 15-fold increase in IgG1, a fivefold to 10-fold increase in IgA, and a fivefold to 10-fold decrease in IgG3. These effects are optimal when the supernatants are added 1 to 2 days after stimulation with LPS. Cells from mouse strains that normally give little or no IgE response in vivo give normal IgE levels in response to LPS plus the supernatant of Concanavalin A-stimulated D9.1 cells in vitro. The enhancement of both IgE and IgG1 can be completely inhibited by relatively low concentrations of interferon-gamma (IFN-gamma). Both the IgE-enhancing activity and IFN-gamma act directly upon purified B cells.     

Inhibition of interleukin 2 production by factors released from tumor cells

In previous studies, cultured melanoma cells were shown to have a suppressive influence on the induction of cytotoxic T cells. Our investigation of the mechanism of these effects revealed that supernatants from certain cultures of melanoma cells contained inhibitory activity against the production of interleukin 2 (IL 2) from phytohemagglutinin (PHA)-stimulated cultures of lymphocytes. These supernatants did not inhibit interleukin 1 production, and also did not inhibit the mitogenic activity of performed IL 2 on IL 2-dependent target cells. Production of the inhibitory activity could be reduced by inhibitors of protein synthesis, but this activity was not inhibited by digestion with the proteolytic enzymes trypsin or pronase. Gel filtration analysis of tumor supernatants revealed that the majority of the inhibitory activity was detected in fractions of approximately 44 and 7 Kd. The addition of supernatants with inhibitory activity to PHA-stimulated cultures of lymphocytes was associated with reduced transition of cells from G1 to S phase of cell division, which could be reversed by the addition of IL 2. Preliminary studies suggest that the release of the factor(s) from melanoma cells may be related to rapid progression of tumor growth in patients, and therefore may be of prognostic significance in tumor host relationships.