Specifically decreased MLC response of lymphocytes from CBA mice injected with cells from the H-2-compatible, M-antigen-incompatible strain C3H. Lack of such effect after injection of H-2-disparate C3H-hybrid cells

Influence of an M-locus difference on the cellular and humoral immunological reactivity against H-2 determined antigens of the mouse

Studies were initiated to determine whether an immune response to the Mls antigen of C3H mice could modify responses of CBA lymphocytes (H-2-compatible) to a foreign H-2 complex. CBA lymphocytes, partially tolerant to the C3H-determined Mls antigen, generated less effector cell activity against C57Bl cells (H-2-incompatible) than lymph node cells from normal CBA donors when infused into irradiated C3H X C57Bl hosts. Effector cell activity was measured as the capacity of the cells in the irradiated spleens to inhibit CBA X C57Bl bone marrow proliferation. In contrast, immunization of CBA mice with C3H X C57Bl cells yielded lower antibody titers against C57Bl cells than immunization with CBA X C57Bl cells. Furthermore, preinjection of CBA mice with C3H X CBA cells strongly reduced the capacity of the animals to produce antibodies against C57Bl cells. Thus, these data support the conclusion that an immune response to a foreign Mls antigen may either enhance or suppress an immune response to H-2-incompatible cells.

Proliferation of C3H x CBA hybrid lymphocytes in the spleens of irradiated CBA mice: linkage to the Mls-gene

Lymphocytes from C3H x CBA F1 mice, lacking detectable Mls-antigens, can specifically inactivate T-cell clones from the H-2-identical strain CBA, which are reactive against the C3H-determined Mls-antigen. Such F1 lymphocytes also proliferate in the spleens of irradiated CBA mice. The age dependence of the mixed lymphocyte culture stimulatory capacity and the capacity to proliferate in irradiated CBA recipients of lymphocytes from C3H x CBA F1 mice were compared. It was observed that appearance of Mls-bearing cells is preceded by the appearance of F1 cells with strong proliferative capacity in irradiated CBA recipients. The in vivo proliferative response is also dependent on the age of the recipient. The varying response is not reflected in the quantity of anti-C3H Mls-reactive cells in CBA mice. A strong linkage between the genes controlling the above proliferative and stimulatory capacities of C3H x CBA lymphocytes was found.

Proliferation of C3H x CBA hybrid lymphocytes in the spleens of irradiated CBA mice: inhibition of this phenomenon by pretreatment of the hosts with C3H x CBA spleen cells

Lymphocytes from C3H x CBA hybrid mice proliferate intensely in the spleens of irradiated CBA mice. Pretreatment of the CBA hosts with C3H x CBA spleen cells, known to specifically reduce the T-cell reactivity of the hosts against the strongly stimulatory Mls-antigen determined by the C3H-genome, abolished the capacity of the host to promote proliferation of C3H x CBA lymphocytes. In contrast, proliferation of C3H x CBA bone marrow cells, as measured by splenic 59Fe incorporation, was unaffected by such pretreatment. By examining the capacity of spleen cell populations of (C3H x CBA) x CBA back-cross mice to inhibit lymphocyte proliferation, as described above, and to express the C3H-determined Mls-antigen, it was concluded that these two traits are associated.

A signaling pathway coupled to T cell receptor ligation by MMTV superantigen leading to transient activation and programmed cell death

Stimulation of T cells by retroviral and bacterial super-antigens is followed by specific T cell elimination, in contrast with stimulation of T cells by peptide, which is usually associated with clonal expansion. We show here that this differential response phenotype is apparent at the level of individual T cell clones following TCR ligation with peptide or MTV antigen. We exploited selective coupling of apoptosis to TCR ligation by MTV7 to examine some of the intracellular biochemical events that underlie this response. MTV-dependent activation resulting in apoptosis was associated with activation of phospholipase A2 and the generation of reactive oxygen intermediates. Inhibition of these biochemical events prevented both MTV-dependent activation and apoptosis without affecting the peptide-dependent response of the same T cell clones. These results indicate that clonal expansion or programmed cell death following TCR ligation may be consequences of distinct TCR-coupled signaling pathways.

Qualitative Shift of Lymphokine Production in Response to Stimulation, as a Consequence of Preactivation In Vivo or In Vitro

Lymphokine production, analysed at the single cell level, was compared in resting and primed T-cell populations. Cells were preactivated in vitro by repeated mitogen stimulations, or isolated as large, low density cells naturally activated in vivo, from normal spleens of unimmunized animals. A similar qualitative shift in the pattern of lymphokines synthesized after restimulation was found as a result of in vivo and in vitro preactivation of cells. Repeated stimulations in vitro resulted in a qualitative shift in the lymphokines produced in response to activation, from a dominance of IL-2 during the first and second culture, to a dominance of IL-4 and IL-5 in the later stimulations. In vivo activation lead to a similar separation of lymphokine production as primarily IL-2 was made by small resting cells, while large cells preferentially produced IL-4 and IL-5. IFN-gamma was produced by both small and large cells. Preactivation in vitro lead to a more rapid appearance of lymphokines during restimulation. In contrast, the in vivo naturally activated cells responded with a slow onset of lymphokine production when stimulated in vitro.

Clonal anergy induced in mature V beta 6+ T lymphocytes on immunizing Mls-1b mice with Mls-1a expressing cells

Tolerance to self-antigens has been shown to develop during ontogeny as a result of the clonal deletion of self-reactive T cells. Tolerance, or better 'nonresponsiveness', to specific antigens can also be induced in adult animals but the mechanism(s) involved are not well understood. Most murine T-helper cells that express the V beta 6 T-cell receptor gene segment are specific for Mls-1a antigens. We have therefore been able to use an anti-V beta 6 monoclonal antibody to follow the fate of Mls-1a specific T cells in adult Mls-1b mice made specifically unresponsive to Mls-1a. We show that the induced unresponsiveness is not due to clonal deletion, but rather to clonal anergy. The anergic V beta 6 T-helper cells express IL-2 receptors and undergo limited blastogenesis in vitro upon stimulation, but do not produce IL-2, in marked contrast to V beta 6 cells from naive mice. Our data appear to represent an in vivo correlate for the induction of anergy that has been observed in T-cell lines in vitro.

T cells define new alloantigens controlled by a gene(s) in the M1s region on mouse chromosome 1

Two different types of T cell clones which recognize Mlsb haplotype gene products were established by using mice congenic at the Mls locus. The antigens defined by these T cells showed differences not only in strain distribution but also in the restriction element for antigen recognition by T cells (i.e. Kd or Dd). The antigens appear to be expressed on various types of lymphocytes.

F1-hybrid anti-parental-strain reactivity. I. Impaired proliferation of CBA lymphocytes in the spleens of irradiated C3H X CBA mice pretreated with CBA spleen cells

Previous investigations have indicated that C3H X CBA hybrid lymphocytes can neutralize lymphocytes which are reactive against the C3H-determined Mls antigen when injected into the H-2-compatible strain CBA. In this study we have inoculated C3H X CBA hybrids with CBA spleen cells and 2 weeks later lethally irradiated the mice and injected them with CBA lymphocytes to study their proliferation in the host spleen. Proliferation of lymphocytes from CBA mice, but not from C57Bl mice, was significantly impaired in such hosts, indicating that the hybrids had become immunized against the parental cells. In contrast, such an effect was not detected by treating CBA X C57Bl mice with CBA spleen cells. Humoral antibodies in the C3H X CBA hybrids capable of blocking the response of CBA lymphocytes against C3H X CBA cells could not be detected, indicating that inhibition of lymphocyte proliferation is cell mediated rather than by humoral factors.

Partial tolerant state against H-2 disparate cells. No impaired specific reactivity in MLC, GVH, or antibody production

Injection of CBA mice with H-2-compatible lymphoid cells from C3H hybrids induces a specific reduction of the mixed lymphocyte culture (MLC) response of their lymphoytes. This is not the case after injection of H-2-disparate C3H-hybrid cells, presumably because they are rapidly eliminated due to the immune response of the host. This investigation shows that CBA mice injected with CBA X C57Bl cells (H-2-disparate) at an age of 0-3 days, but not older, develop a specifically reduced MLC response after infusion of C3H X C57Bl cells as adults, indicating that they were tolerant to the C57Bl-determined antigens. However, lymphocytes from such mice showed a normal reactivity against C57Bl as assessed by MLC, graft-versus-host tests, and capacity to produce specific antibodies.

Activation of T lymphocytes to M locus determinants in vivo. I. Quantitation of T cell proliferation and migration into thoracic duct lymph

Proliferative responses to M locus (Mls) determinants were investigated in vivo by injecting T cell-containing populations intravenously into irradiated H2-identical, Mls-incompatible mice. Responses were studied 1-6 days later by measuring levels of radioactivity in the spleen and lymph nodes of the recipient 45 min after intravenous injection of tritiated thymidine. High responses were observed against Mlsa and Mlsd determinants, i.e. determinants which give strong proliferative responses in vitro. With injection of thoracic duct lymphocytes (TDL), lymph node or thymus cells, the responses, both in the spleen and the lymph nodes, reached a peak at day 3-4 and then fell sharply. This was in marked contrast to the stimulation observed with H-2-incompatible mice where, with TDL or lymph node cells (though not with thymus cells), responses were low at day 3-4 but reached high levels at day 6. Significant responses were also observed against Mlsb and Mlsc determinants, i.e. determinants which stimulate poorly in vitro. The kinetics of this response differed from that against Mlsa or Mlsd determinants in in that proliferation was very low at day 4 but high at day 6. No evidence was found that the responses observed reflected "back-stimulation" by the host. Since congenic resistant strains were not used, the possibility that the stimulation observed was in fact due to minor transplantation antigens rather than Mls determinants could not be excluded. Large numbers of blast cells appeared in thoracic duct lymph of mice sustaining responses to Mlsa or Mlsd determinants. Nearly all of these cells had recently synthesized DNA and entered the lymph after day 3.

Complex nature of the production of 'effector' cells and their interaction with target cells in the M-antigen system of the mouse

The capacity of lymphocytes from mouse strain CBA to generate 'effector' cells against the H-2-compatible, M-antigen-incompatible strain C3H and their interaction with such target cells were investigated. It was observed that CBA lymphocytes injected in, and 5 days later obtained from, the spleens of irradiated C3H X CBA hybrids ('educated cells') could strongly inhibit the growth of C3H X CBA bone marrow cells but were almost nonresponsive to C3H X C57BI bone marrow targets (H-2-incompatible). CBA lymphocytes educated in irradiated C3H X C57BI hosts displayed reactivity against C3H X C57BI and CBA X C57BL but not against C3H X CBA bone marrow target cells. Additional tests indicated that the M antigen determined by C3H is expressed to approximately the same extent on C3H X CBA and C3H X C75BL cells and that the M antigen on C3H does not cross-react immunologically with antigens on C57BL cells. Moreover, it was observed that CBA X C57BI lymphocytes were triggered to cell proliferation by C3H antigens but were unable or had a highly reduced capacity to develop 'effector' cells in response to this antigenic stimulus. These results indicate that generation of 'effector' cells and their interaction with target cells are very complex processes.

Reduced capacity to produce specific 'effector' cells after injection of CBA mice with C3H cells

Lymphocytes from mice of strain CBA are strongly MLC-responsive to lymphocytes from the H-2-compatible but M-antigen-incompatible strain C3H. This strong reactivity disappears after infusion of CBA mice with C3H lymphocytes. This study shows that the host-versus-graft reactivity (swelling of local lymph node after antigen injection) is specifically reduced after injection of CBA mice with C3H times CBA spleen cells. However, lymphocytes from such mice showed a specifically increased GVH reactivity (inhibition of erythroid cell growth) compared with lymphocytes from unimmunized mice. Lymphocytes from normal CBA mice showed a high proliferative rate in the spleens of irradiated C3H times CBA mice. Such 'educated' cells showed strongly increased specific GVH reactivity. Lymphocytes from CBA mice previously injected with C3H times CBA cells showed reduced capacity to proliferate when injected into irradiated C3H times CBA hybrids and a poor capacity to develop new 'effector' cells reactive against C3H times CBA bone marrow target cells. The results indicate that the presence of specifically 'MLC-responsive' lymphocytes in a lymphoid cell population is a prerequisite of its production of 'effector' cells able to respond in this GVH assay.

Antibody response in C3H mice injected with CBA lymphoid cells as detected by membrane immunofluorescent staining

Lymphocytes from CBA mice are strongly responsive to cells from the H-2-identical strain C3H in vitro (MLC), whereas C3H lymphocytes are poorly reactive against CBA cells. Immunization of CBA mice with C3H lymphocytes did not yield any detectable specific antibodies. On the other hand, C3H mice immunized with CBA cells produced specific antibodies as detected by membrane immunofluorescence. Mice of the strains AKR and DBA/2 also possess this specific membrane alloantigen. We thus conclude that it is now possible to discriminate among lymphocytes of CBA and C3H origin.