Splenic modifications induced by cyclophosphamide in C3H/He, nude, and "B" mice.

The spleen cell population of adult C3H/He mice injected with a single sublethal dose of cyclophosphamide (CY) has been analyzed. An initial phase of spleen atrophy is followed by a considerable hypertrophy, and a progressive return to normal. During the phase of spleen atrophy, both B and T cell compartments are depleted, as estimated by the percentages of cells killed by anti-Thy 1-2 and anti-Ig antisera plus complement. During the stage of regeneration, the percentage of Ig + cells increases rapidly, and at the peak of splenomegaly, the percentage of Ig + cells is high whereas almost no Thy 1-2 + cells are detectable. Progresively, the spleen cell content returns to the original values. In thymo-deprived mice (nude mice and B mice) the percentage of null cells increases during the stage of regeneration, and B mice develop a large number of Ig +-bearing cells. Histologic examination shows that follicles (B-dependent areas) disappear 1 to 2 days before periarteriolar sheaths (T-dependent areas). At the peak of splenomegaly the architecture of the spleen is destroyed, and the interstitial tissue is composed of a dense and uniform layer of lymphoid cells. Progressively, the architecture returns to normal. In nude mice, the disappearance of follicles, and the appearance of a homogenous layer of lymphocytes has been observed. When analyzed for their pattern of electrophoretic mobilities (E.M.), spleen cells from untreated mice reveal two peaks of E.M. 0.80 and 1.15 micron x s-1 x V-1 x cm-1. After CY treatment, during the step of splenic hypertrophy, these two peaks disappear, and a single peak of intermediate mobility appears. In T-deprived mice, a single peak of the same mobility is detected at this stage. The nature and origin of cells which appear during the phase of regeneration are unclear, but their appearance in T-deprived mice argues against thymo dependence. These spleen cells have the ability to suppress the response of normal spleen lymphocytes to T and B cell mitogens.     

Tumor necrosis factor alpha-deficient, but not interleukin-6-deficient, mice resist peripheral infection with scrapie

In most peripheral infections of rodents and sheep with scrapie, infectivity is found first in lymphoid tissues and later in the central nervous system (CNS). Cells within the germinal centers (GCs) of the spleen and lymph nodes are important sites of extraneural replication, from which infection is likely to spread to the CNS along peripheral nerves. Here, using immunodeficient mice, we investigate the identity of the cells in the spleen that are important for disease propagation. Despite possessing functional T and B lymphocytes, tumor necrosis factor alpha-deficient (TNF-alpha(-/-)) mice lack GCs and follicular dendritic cell (FDC) networks in lymphoid tissues. In contrast, lymphoid tissues of interleukin-6-deficient (IL-6(-/-)) mice possess FDC networks but have impaired GCs. When the CNSs of TNF-alpha(-/-), IL-6(-/-), and wild-type mice were directly challenged with the ME7 scrapie strain, 100% of the mice were susceptible, developing disease after closely similar incubation periods. However, when challenged peripherally (intraperitoneally), most TNF-alpha(-/-) mice failed to develop scrapie up to 503 days postinjection. All wild-type and IL-6(-/-) mice succumbed to disease approximately 300 days after the peripheral challenge. High levels of scrapie infection and the disease-specific isomer of the prion protein, PrP(Sc), were detectable in spleens from challenged wild-type and IL-6(-/-) mice but not from TNF-alpha(-/-) mice. Histopathological analysis of spleen tissue demonstrated heavy PrP accumulations in direct association with FDCs in challenged wild-type and IL-6(-/-) mice. No PrP(Sc) accumulation was detected in spleens from TNF-alpha(-/-) mice. We conclude that, for the ME7 scrapie strain, mature FDCs are critical for replication in lymphoid tissues and that in their absence, neuroinvasion following peripheral challenge is impaired.     

Ontogeny of B lymphocytes. I. In vitro appearance of Ig-bearing lymphocytes

During the immediate postnatal period, a striking increase in the fraction and number of splenic lymphocytes which bear easily detectable surface immunoglobulin (Ig) occurs in BALB/c and CDF₁ mice. Thus, in mice < 8 hr of age, approximately 4% of splenic lymphoid cells bear surface Ig whereas 17% of splenic lymphocytes of mice 24 hr of age are positive for surface Ig. This increase in Ig-bearing lymphocytes can be obtained in vitro. Thus, cultures of spleen or liver cells from neonatal mice display a substantial increase in the percent and in the absolute number of cells with easily detectable surface Ig. The in vitro increase in Ig-bearing cells is largely inhibited by mitomycin C or puromycin treatment of neonatal cells. Interestingly, pretreatment of these cells with anti-κ antibody, with or without complement, inhibited the increase in Ig-bearing cells. These results indicate that a substantial portion of Ig-bearing lymphoid cells present at 24 hr of age derive from cells already present in the spleens and livers of neonatal mice. Many of these “precursor” cells appear to bear some surface Ig.     

Pre-B cells: bone marrow persistence in anti-mu-suppressed mice, conversion to B lymphocytes, and recovery after destruction by cyclophosphamide.

Chronic treatment of mice from birth with anti-mu antibodies aborts development of B lymphocytes and plasma cells. In these studies we show that bone marrow from anti-mu-treated mice contains a population of cells with cytoplasmic IgM, but which lack detectable cell-surface IgM. These cells are analogous to pre-B cells, defined in ontogenetic studies as the immediate precursors of B lymphocytes. Pre-B cells from bone marrow of anti-mu treated mice retain their functional integrity, as evidenced by their ability to give rise to sIgM+, LPS-responsive lymphocytes in culture. We also show that cyclophosphamide treatment destroys pre-B cells and that recovery of pre-B cells in bone marrow precedes the regeneration of sIgM+ B lymphocytes. Generation of B lymphocytes in adult mice apparently occurs exclusively in the bone marrow because induction of extramedullary hemopoiesis in spleen was not accompanied by the appearance of pre-B cells in that organ.     

Accelerated programmed cell death of MRL-lpr/lpr T lymphocytes.

MRL-lpr/lpr (lpr) mice develop a polyclonal accumulation of abnormal peripheral T lymphocytes, which bear surface alpha beta TCR, CD3, and the B220 isoform of CD45, but lack CD4, CD8, and CD2. These T cells have a constitutively phosphorylated CD3 zeta chain and manifest a defect in signal transduction that results in a lack of IL-2 production and proliferation. We investigated whether this signaling abnormality might contribute to their accumulation via a defect in T cell elimination in the periphery. T cell deletion occurs through a process of programmed cell death with DNA degradation, or apoptosis. Viable lymphocytes from lpr mice were found to undergo rapid programmed cell death in culture within 4 h without additional activation, which was not observed in lymphocytes from normal MRL-+/+ or C57BL/6-+/+ mice. Both nonmature B220+ and mature B220- T lymphocytes from lpr mice display this accelerated programmed cell death, indicating that this is a defect affecting all peripheral T lymphocytes in lpr mice. In vitro apoptosis of lpr T cells could be inhibited with PMA, a stimulator of protein kinase C. Thus, the massive accumulation of T lymphocytes in the lymphoid tissue of lpr mice is not due to a defect in their ability to undergo programmed cell death in vitro. The activation state of lpr T cells may contribute to their rapid degradation of DNA in vitro.     

Differentiation of lymphocytes in mouse bone marrow. I. Quantitative radioautographic studies of antiglobulin binding by lymphocytes in bone marrow and lymphoid tissues

The density of surface immunoglobulin on small lymphocytes in the bone marrow and other lymphoid tissues has been compared by radioautographic measurements of antiglobulin binding.Cell suspensions from CBA mice were exposed to ¹²⁵I-labeled rabbit anti-mouse globulin in a wide range of concentrations for 30 min at 0 °C. With increasing concentration of antiglobulin-¹²⁵I the percentage of labeled antiglobulin-binding small lymphocytes in spleen and lymph node suspensions reached well-defined plateau levels. Very few normal or cortisone-resistant thymus cells were labeled under identical conditions. Bone marrow small lymphocytes showed a linear increment in labeled cells throughout the antiglobulin-¹²⁵I dose range, their labeling intensity varied widely, and approximately one half remained unlabeled at high antiglobulin-¹²⁵I concentrations. In 6 wk-old congenitally athymic mice the bone marrow small lymphocyte labeling pattern resembled that in CBA mice, while nearly all (91–97%) small lymphocytes in lymph nodes, thoracic duct lymph and blood, and 75% of those in the spleen, became labeled under plateau conditions. Treatment of cells from 10 wk-old CBA mice with AKR anti-θ C3H serum and complement resulted in almost complete (93%) antiglobulin-labeling of residual small lymphocytes from the spleen but had little effect on bone marrow lymphocyte labeling. Under germfree conditions the proportion of antiglobulin-binding small lymphocytes was slightly elevated in all lymphoid tissues of CBA mice.The results demonstrate that many of the small lymphocytes in mouse bone marrow have readily detectable surface immunoglobulin molecules which vary considerably in density from cell to cell, while others neither have detectable surface immunoglobulin, nor are they θ-bearing, thymus-dependent or recirculating cells. The concept of bone marrow small lymphocytes as a maturing cell population is discussed.     

Deregulated Bcl-2-immunoglobulin transgene expands a resting but responsive immunoglobulin M and D-expressing B-cell population.

We characterized the basis for the follicular lymphoproliferation in transgenic mice bearing a Bcl-2-immunoglobulin (Bcl-2-Ig) minigene representing the t(14;18) of human follicular lymphoma. Discriminatory S1 nuclease protection assays revealed that the Bcl-2-Ig transgene was overexpressed relative to endogenous mouse Bcl-2 in spleen and thymus. Western (immunoblot) analysis demonstrated the overproduction of the human 25-kilodalton Bcl-2 protein, which arose from the transgene, in spleen, thymus, and the expanded B-cell subset. Despite the generalized lymphoid pattern of deregulation, two-color flow cytometry and density gradient centrifugation indicated that the expanded lymphocytes were predominantly small, resting B cells coexpressing B220, immunoglobulin M (IgM), IgD, Ia, and kappa. Cell cycle analysis confirmed that about 97% of these expanded B cells reside in G0/G1. An extensive characterization of transgenic lines revealed a fourfold excess of IgM-IgD-expressing B cells in spleen and dramatically increased numbers in bone marrow. While resting, these cells proliferated in response to lipopolysaccharide and anti-IgM and demonstrated normal B-cell colony formation in soft agar. Moreover, these B cells, which demonstrated an extended survival in vitro even in the absence of stroma, were also resting in G0, yet were capable of proliferative responses. These findings provide consistent evidence that the accumulation of B cells after Bcl-2 overproduction is secondary to prolonged cell survival and not increased cell cycling. This suggests a unique role for Bcl-2 as a proto-oncogene that enhances cell survival independent of promoting cell division.     

Undernutrition without malnutrition restricts the numbers and proportions of Ly-1 B lymphocytes in autoimmune (MRL/I and BXSB) mice

MRL/Mp-lpr/lpr (MRL/l) and BXSB mice represent inbred mouse strains in which lymphoproliferative disease and autoimmune disease that includes lethal renal disease routinely occurs by 6 months of age. Chronic energy intake restriction increases longevity and health span of MRL/l and BXSB mice as it does in mice of other short-lived as well as long-lived strains. Chronic energy intake restriction forestalls development of the lymphoproliferative process, prevents development of renal lesions, decreases levels of circulating immune complexes, and permits maintenance of vigorous immunologic function with age. We have reported that in autoimmune-prone mice, a population of Ly-1 B lymphocytes that is associated with autoimmune disease and is greatly expanded among cells of the spleen, peritoneal exudate, and peripheral blood can be reduced in proportion as a consequence of undernutrition without malnutrition. Herein, we demonstrate that in MRL/l and BXSB mice, chronic energy intake restriction imposed at weaning inhibited accumulation of Ly-1 B lymphocytes throughout the lymphoid system, i.e., among cells of the spleen, thymus, mesenteric lymph nodes, bone marrow, peritoneal exudate, and peripheral blood when these tissues or fluids were studied at age 3 or 5 months. These results extend our previous finding that autoimmune-prone mice possess unusually large numbers of Ly-1 B cells in their lymphoid tissues which can be reduced in frequency as a function of diet toward the levels present in long-lived autoimmune-resistant mice.     

Treatment of NZB/NZW mice with total lymphoid irradiation: long-lasting suppression of disease without generalized immune suppression

We used total lymphoid irradiation (TLI; total dose = 3400 rad) to treat the lupus-like renal disease of 6-mo-old female NZB/NZW mice. Similar to our past studies, this treatment resulted in a marked prolongation of survival, decrease in proteinuria, and decrease in serum anti-DNA antibodies compared with untreated littermate controls. Although there was no evidence of disease recurrence in TLI-treated mice until after 12 mo of age, the in vitro proliferative response to phytohemagglutinin by NZB/NZW spleen cells recovered within 6 wk such that responses were greater than control NZB/NZW animals. A similar recovery and overshoot after TLI were evident in the primary antibody response to the T cell-dependent antigen sheep red blood cells (SRBC). Both the total and IgG anti-SRBC antibody responses after TLI were greater than those of untreated NZB/NZW controls, and were comparable with those of untreated non-autoimmune mice. Despite this increased response to mitogens and antigens after TLI, we noted a decrease in spontaneous splenic IgG-secreting cells and a decrease in IgG but not IgM antinuclear antibody production. Nonspecific suppressor cells of the mixed leukocyte response were detectable in the spleens of NZB/NZW mice early after TLI. However, the disappearance of suppressor cells was not associated with recrudescence of disease activity. Furthermore, transfer of large numbers of spleen cells from TLI-treated NZB/NZW mice did not result in disease suppression in untreated age-matched recipients. In summary, treatment of NZB/NZW mice with TLI results in a prolonged remission in autoimmune disease, which is achieved in the absence of generalized immunosuppression.     

The lichen rock tripe (Lasallia pustulata) as survival food: effects on growth, metabolism and immune function in Balb/c mice

The present study was performed to investigate whether the lichen rock tripe (Lasallia pustulata) can be used as food during survival situations. The effects of 30% lichen supplementation given to female Balb/c mice were studied on growth rate, metabolism and immune functions. After 3 weeks on this diet, it was found that the lichen supplementation did not affect the growth rate or the well-being of the animals. The growth rate tended to be higher in the lichen group when compared to control mice. Food consumption was similar in both groups, but with a trend towards slightly higher intake (12%) in the lichen group. The heart, liver, kidney and lymphoid organ (spleen and thymus) weights were not affected by the lichen. Histological hematoxylin eosin staining showed that all these organs were normal. Plasma glucose levels were unchanged, but plasma urea levels decreased by 24% (p < 0.05) with the lichen diet. Red and white blood cells and the number of lymphoid cells in the thymus and spleen were normal. The activity of thymocytes and spleen T-lymphocytes were not affected by the lichen diet, but spontaneous cell-mediated cytotoxicity (NK cells) tended (n.s.) to increase and spleen B-lymphocyte activity increased by 40% (p < 0.05). This study shows that the lichen rock tripe has immune stimulating effects important for host defence reactions and can be used as food in survival situations without any adverse effects on the metabolism.     

The allogeneic effect on tumor growth. I. Inhibition of a murine plasmacytoma, MOPC 315, by the graft-vs-host reaction.

The allogeneic effect has been employed as a potent immunopotentiator in preventing the growth of a murine plasmacytoma and prolonging host survival. Parental BALB/c spleen cells were passively transferred to (BALB/c x A/H)F1 hybrid mice, who were then given a highly lethal dose of MOPC 315 plasmacytoma, a tumor of BALB/c origin. The resultant graft-vs-host reaction protected the recipient mice against growth of the tumor and significantly prolonged survival. This phenomenon was dependent upon the dose of BALB/c lymphoid cells employed, the route of administration, and the time interval between lymphoid cell transfer and tumor inoculation. A wide range of lymphoid cell doses and time intervals were effective, and repeated doses of allogeneic cells provided better protection than a single dose.     

Depletion of macrophages expressing I-J antigen results in efficient generation of alloreactive cytotoxic T lymphocytes

The role of suppressor macrophages (S-M phi) produced during generation of cytotoxic T lymphocytes (CTL) stimulated with allogeneic lymphocytes was investigated. Splenic CTL from C3H/He mice (H-2k) were generated by in vivo immunization and subsequent in vitro stimulation by splenic lymphocytes from C57B1/6 mice (H-2b) in mixed lymphocyte reaction (MLR). In addition to in vitro standard 51Cr release assay, the CTL activity was mainly measured in vivo using the Winn assay against EL-4 thymoma cells in B6C3F1 mice (H-2b/k). In mice injected with CTL plus EL-4 cells survival rate was 20% compared with no survival of mice treated with normal spleen cells plus EL-4 cells. The antitumor activity of the CTL was significantly increased when immunized mice were treated with a 5 mg/kg ip dose of indomethacin at the time of immunization (80% survival). Macrophages were depleted from spleen cells of immunized mice by plastic adherence or carbonyl-iron treatment, replaced with an equivalent number of M phi from normal mice, and then introduced into a 5-day MLR. When the antitumor activity of the cells isolated from this MLR was measured in the Winn assay, 90-100% survival in EL-4-bearing mice was observed. In contrast, none of the mice inoculated with EL-4 alone and 20% of the mice that received CTL obtained after alloimmunization followed by MLR in addition to EL-4 survived. These results of CTL activity were confirmed by in vitro cytotoxicity tests. When the M phi isolated from spleens of immunized mice were analyzed for I-Jk antigen expression, a 2.5-fold increase was detected, compared with splenic M phi obtained from normal C3H/He mice. In contrast, Ia and I-Ak antigen expression was equivalent in M phi isolated from normal or immunized C3H/He mice. When immune spleen cells were treated with anti-I-Jk antiserum followed by complement and then, subjected to the MLR, the antitumor activity of CTL was significantly enhanced (80% survival). However, treatment of these cells with anti-I-Ak antiserum and complement did not alter CTL activity. These data suggest that the increase of S-M phi expressing I-Jk+ antigen to be induced during alloimmunization results in suppression of allospecific CTL-generation in MLR.     

Defective T helper activity in the spleen of BALB/c mice immune to a syngeneic fibrosarcoma

Summary BALB/c mice were immunized with the syngeneic 3-methylcholanthrene-induced fibrosarcoma CA-2 by the growth and excision method. When lymphoid cells from different organs of these tumor-free mice were tested in a direct ⁵¹Cr-release assay, peritoneal exudate cells but not spleen cells displayed specific cytotoxicity against the syngeneic tumor target. A cytotoxic response could be obtained by tumor-immune spleen cells when cultured in a mixed lymphocyte tumor cell culture (MLTC) at high but not low density although at the same effector/stimulator ratio. Lack of cytotoxic activity in low density MLTC was not due to an impairment of cytotoxic precursors since cytotoxicity was rescued by adding exogenous interleukin-2 in experimental conditions in which no lymphokine-activated killer cells could develop relevant anti-CA-2 lysis. When low density MLTC were supplemented with either 800 R-irradiated cells or nonirradiated, negatively selected Lyt 1⁺ cells from the same immune mice, induction of a cytotoxic response against CA-2 occurred and interleukin-2 production became detectable. Additional studies indicated that spleen cells of CA-2-immune mice were also impaired in their ability to provide help to syngeneic thymocytes for the generation of cytotoxic T lymphocytes against C57BL/6J alloantigens. Dilution effect of helper cells due to immunization procedures was excluded since spleen cells of mice immunized against another BALB/c tumor, the YC8 lymphoma, or against DBA/2 minor histocompatibility antigens provided good help to thymocytes against the same alloantigens. These results indicate that tumor-immune animals may also have selective T helper defects in an important lymphoid organ like spleen.     

In vitro induction of cell-mediated immunity to murine leukemia cells

Summary An adoptive chemoimmunotherapeutic model based on the use of chemotherapy and lymphocytes specifically sensitized against tumor cells in vitro was tested in mice transplanted with syngeneic leukemia cells. C57BL/6 and A strain mice were inoculated i.p. or i.v. (day 0) with lethal doses (1×10³–1×10⁵) of EL4 and YAC leukemia cells, respectively. Leukemic mice were subsequently treated (day 1 or day 3) with partially curative doses (80–140 mg/kg) of cyclophosphamide (Cy), followed by i.p. or i.v. administration of 1–3×10⁷ cytotoxic lymphocytes (CL) induced in macro-mixed leukocyte-tumor cell cultures (MLTC). The following results were obtained: untreated mice died with tumor within 20 days; mice receiving sensitized lymphocytes only showed a modest prolongation of survival and only 5–15% of the animals were cured; treatment with Cy alone or with Cy and normal lymphocytes prolonged survival considerably and cured 20–60% of the mice; mice subjected to Cy in conjunction with in vitro-sensitized lymphoid cells, either syngeneic or allogeneic, had survival rates of 80–100% (100 days). Under the conditions employed, no severe manifestations of clinical graft-versus-host (GVH) reaction were observed. These findings imply that in vitro-sensitized immunocytes and cytoreductive drugs can operate cumulatively.     

Cutting edge: ectopic expression of the chemokine TCA4/SLC is sufficient to trigger lymphoid neogenesis

To test whether accumulation of naive lymphocytes is sufficient to trigger lymphoid development, we generated mice with islet expression of the chemokine TCA4/SLC. This chemokine is specific for naive lymphocytes and mature dendritic cells (DC) which express the CCR7 receptor. Islets initially developed accumulations of T cells with DC, with scattered B cells at the perimeter. These infiltrates consolidated into organized lymphoid tissue, with high endothelial venules and stromal reticulum. Infiltrate lymphocytes showed a naive CD44low CD25- CD69- phenotype, though half were CD62L negative. When backcrossed to RAG-1 knockout, DC were not recruited. Interestingly, islet lymphoid tissue developed in backcrosses to Ikaros knockout mice despite the absence of normal peripheral nodes. Our results indicate that TCA4/SLC can induce the development and organization of lymphoid tissue through diffential recruitment of T and B lymphocytes and secondary effects on stromal cell development.     

Purine metabolic enzymes in lymphocytes. I. Adenosine deaminase and purine nucleoside phosphorylase activities in mouse lymphocyte subpopulations

The distribution of adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) activities in lymphoid organs and lymphocyte subpopulations in mice, and the effect of phytohemagglutinin P (PHA-P) and concanavalin A (Con A) on the enzyme activities were studied. ADA activity was distributed equally in cells from all organs used and no mouse strain differences were observed. In contrast, PNP activity varied with the mouse strain, being highest in C57BL/6 mice and lowest in BALB/c mice, and with the organ in ICR mice, being high in peripheral blood lymphocytes and spleen lymphocytes, low in mesenteric lymph node cells and absent or very weak in thymus cells. T and B lymphocytes were prepared from spleen of ICR mice. High ADA activity was found in both T and B lymphocytes, whereas PNP activity in the T lymphocytes was about one-third of that in the B lymphocytes. PNP activity in thymus cells was increased to the normal level of T lymphocytes in the spleens by cultivation without stimulant. The development of PNP activity in thymus cells was partially inhibited by Con A but was not affected by PHA-P. ADA activity in thymus cells was enhanced by in vitro stimulation with PHA-P but not with Con A. In contrast, in spleen lymphocytes the development of ADA activity was enhanced by stimulation with PHA-P and Con A, and that of PNP activity was enhanced by PHA-P but not by Con A.     

Abrogation of neonatally induced permanent transplantation tolerance in mice: quantitative aspects.

Neonatal transplantation tolerance was induced in CBA (H-2k) mice by the intravenous injection of 20 million (CBAxA)F1 spleen cells to the transplantation antigens of the A mouse strain. Those mice which carried an A (H-2a) skin allograft without any sign of rejection for at least 120 days, were considered to be permanently tolerant and were selected for further experiments. Abrogation of permanent transplantation tolerance was achieved by injecting the tolerant mice with different doses (50, 100 and 200 millions, respectively) of normal syngeneic (CBA) lymphoid (spleen) cells. Dynamics of the rejection of the test skin allografts tolerated so far revealed well reproducible dose-response curves. Further groups of tolerant CBA mice were given 10, 50, 100, or 200 million "sensitized" (G + 16) CBA spleen cells: "sensitization" by A-skin allografting was performed 16 days before. The sensitized spleen cells abolished the state of tolerance more vigorously and effectively than the normal CBA spleen cells did. In a third group of experiments, the abrogating capacity of 50 million sensitized CBA spleen cells 16, 120, 240, or 360 days after sensitization was compared. The efficacy of the sensitized cells in abolishing the state of tolerance decreased continuously, but, even 360 days after sensitization a remarkably strong immunologic memory was demonstrable. The excellent quantitative correlations found between the number of the injected lymphoid cells and the dynamics of the abrogation of tolerance offer a highly promising new possibility for studying the immunological activity, the immunologic memory, etc., of the different lymphoid cell (sub)populations in performing the transplantation immune reactions.     

The null cell compartment of the mouse spleen

Null lymphocytes were defined as lymphocytes without detectable T- or B-cell markers using a battery of techniques. The null cell compartment was divided into pre-T cells, pre-B cells, and other null cells based upon their acquisition of membrane markers when incubated with ubiquitin. The null cell subpopulations were remarkably consistent in spleen cell suspensions from young adult mice of various strains. Commitment to T- or B-cell differentiation took place at the null cell stage and did not require thymic input. Pre-T cells, but not pre-B cells, were steroid sensitive. Pre-T cells accumulate with congenital thymic deficiency. This differed from senescent thymodeprivation where the outstanding finding was an accumulation of uninducible null cells. Neonatal mouse spleens were deficient in pre-T and pre-B cells but had an accumulation of uninducible cells.     

Experimental Models for Prevention of Graft-versus-Host Reaction in Bone Marrow Transfusion

Induction and suppression of splenomegaly and cytotoxicity against C57BL/6 cells were studied in (AKR × C57BL/6) F1 hybrid adult mice after the transfer of AKR lymphoid and bone marrow cells. 1) Splenomegaly and cytotoxicity were dissociated in the developmental stages of the graft-versus-host reaction. When lymphoid and bone marrow cells of normal AKR mice were injected into F1 recipients, splenomegaly was prominent on days 5 and 7, but cytotoxicity of spleen cells was not detected. Splenomegaly became less prominent but the cytotoxicity became detectable on day 14 after the injection. 2) Cytotoxic activity of spleen cells of F1 recipients was suppressed by the treatment of AKR donors with C57BL/6 lymphoid cells in Freund's complete adjuvant. Splenomegaly, however, was substantially enhanced by such a treatment of the donors. On the other hand, induction of the cytotoxic activity was facilitated by the treatment of donors with C57BL/6 skin grafts. 3) F1 hybrid mice could be protected from the graft-versus-host reaction by the injection of AKR anti-C57BL/6 serum or pretreatment of AKR donors with sonicated cellular antigens of C57BL/6.