Genetics of graft-versus-host reactions: I. Production of splenomegaly and mortality in mice disparate atH-2I subregions

A study on graft-versus-host reaction (GVHR) by Simonsen's splenomegaly assay. Cells and antigen systems involved in induction of GVHR

Cells and histocompatibility antigen systems involved in graft-versus-host reactions (GVHR) were analyzed using Simonsen's splenomegaly assay employing various combinations of donor and F1 hybrid recipients mice. Most of the cells proliferating in spleens of mice undergoing GVHR were J11d+, and had histological features of cells of the hematopoietic lineage. The proportions of CD3+ T cells were decreased in the spleens. Disparity at minor histocompatibility determinants of AKR, I-E and H-2D regions between B10.A(4R) donors and (4R X AKR) F1 recipients evoked only negligible GVHR. On the contrary, disparity at H-2K and/or I-A regions appeared to be sufficient to permit induction of full GVHR. When surface markers of donor spleen cells were analyzed, it was shown that Thy-1+ and/or MEL-14+ cells caused a strong effect on GVHR. Further, either CD4+ or CD8+ T cell subset could induce significant GVHR. However, synergistic influences of these two T cell subsets on one another in GVHR were observed. The present results raise the possibility of using Simonsen's assay along with a number of reagents to identify the contribution of subsets of T lymphocytes and in analyzing precise contributions of cellular components from both donor and recipient, and also of the target antigen systems of the recipient that contribute to early events involved in GVHR.

Inhibition of antisuppression by the acute murine graft-versus-host reaction

Profound suppression of both humoral and cell-mediated immunity is a significant systemic effect of graft-versus-host reactions. Although no complete explanation has been advanced for this immunosuppression suppressor cells have been implicated. The data presented in this paper indicate that acute GVH reactions in (C57BL/6J X A/J) F1-hybrid mice induced by the injection of A/J cells severely disrupts the function of the antisuppressor T-cell pathway at both its induction and effector stages. Results show that within 3 weeks of induction of the reaction, Ly1+-T antisuppressor inducer cells lose their ability to generate the serum factor that mediates antisuppression. This factor is normally taken up by and activates Ly2+ T cells which then inhibit suppressor T-cell function. The data also reveal that Ly2+ T cells collected 2 weeks after induction lose their ability to be activated by the antisuppressor factor produced in normal mice. These cells are thus unable to function as antisuppressor effector cells. The uptake of the antisuppressor factor by Ly2+ T cells depends on the expression of Ia antigens on the surface of these cells. Experiments have shown that these antigens are absent from the surface of T cells derived from mice with GVH reactions. This finding may provide an explanation for the inability of these cells to function as antisuppressor effectors. Antisuppression is an important T-cell pathway that is intimately associated with the regulation of immune function. It is possible that the immunosuppression arising in mice with GVH reactions may stem, in part, from unopposed suppressor T-cell activity that results from widespread interference by the reaction with a pathway that normally inhibits suppressor cell activity.

Cytotoxic T-lymphocyte tolerance to minor H-43a alloantigen is induced exclusively in the context of the self major histocompatibility complex class I H-2Kb molecules

We elucidated previously that cytotoxic T lymphocyte precursors (CTLp) against H-43a allo-antigen, which we had discovered as a new mouse minor H antigen, were primed in H-43b mice only in the context of self H-2Kb restriction element, and that anti-H-43a CTLp tolerance was induced in H-43b mice by injection with H-43a spleen cells (SC) from H-43 congenic mice, i.e., under the condition of disparity at only the H-43 locus. The present study attempted to determine whether the H-2Kb restriction element for anti-H-43a CTLp priming is also implicated in the induction of anti-H-43a CTLp tolerance. For this purpose, we used a newly established H-43b C3W (H-2k) strain which is H-43 congenic to H-43a C3H/HeN. When (C3W X B10.MBR)F1 (H-43b, H-2Kk/b, Ik/k, Dk/q) mice were injected with H-43a-bearing (C3H/HeN X B10.AKM)F1 (H-43a/b;H-2Kk/k,Ik/k,Dk/q)SC, their selfH-2Kb-restricted anti-H-43a CTLp were were primed (cross-priming). By contrast, injection of H-43a-bearing (C3H/HeN X B10.MBR)F1 (H-43a/b; H-2Kk/b,Ik/k, Dk/q)SC, which differ from (C3H/HeN x B10.AKM) F1 SC solely at H-2K and possess H-2Kb molecules, did not prime but specifically inactivated the anti-H-43a CTLp of (C3W x B10.MBR)F1 mice. These results indicate clearly that anti-H-43a CTLp tolerance is induced exclusively in the context of the H-2Kb element expressed on the antigenic H-43a SC.

Graft-vs.-host reactions: mechanisms and contemporary theories

A graft-vs.-host (GvH) reaction can be initiated by injection of immunocompetent lymphocytes into a histoincompatible host that is unable to reject these cells. The reaction is characterized by splenomegaly, hepatomegaly, lymph node atrophy, body weight loss, dermatitis, and diarrhea, often leading to mortality. The onset and severity of the GvH reaction are determined by differences in histocompatibility antigens between the donor and the acceptor, and by the number and nature of the transplanted allogeneic cells. Many different in vivo and in vitro systems have been devised for experimental studies of the GvH reaction. In several of these models, however, different parameters are measured. Furthermore, the conclusions drawn from these investigations sometimes contradict each other. This paper reviews the experimental data, and discusses the mechanisms underlying the GvH reaction.

Mixed leukocyte reaction, graft-versus-host reaction, and skin allograft rejection in the lizard, Chalcides ocellatus

In optimal seasonal conditions, splenocytes derived from adult lizards, Chalcides ocellatus, responded to vigorous proliferation in two- and one-way mixed leukocyte reaction cultures (MLRC). Data based on a large number of reciprocal MLRC provided evidence for the presence of strong and diverse lymphocyte activating determinants. These findings were fully confirmed in studies of systemic graft-versus-host reaction as intraperitoneal injection of splenocytes into newborn allogeneic recipients consistently induced splenomegaly, retarded growth and mortality. In favourable ambient conditions, adult lizards were also able to reject skin allografts in a subacute manner (mean survival time +/- S.E. = 28.8 +/- 0.88). The results clearly indicate that the lizard, Chalcides ocellatus, is endowed with an advanced type of cell-mediated immunity, and possesses strong and polymorphic histocompatibility antigens. Cellular alloreactivity in MLRC and towards skin grafts was, however, abrogated in winter and significantly diminished during spring through mid-summer as compared to mid-summer till autumn. The present study, thus, suggests that immunological defects attributed to reptiles might be more apparent than real, and essentially ascribable to the fact that the immune capacity of these ectothermic vertebrates is profoundly modulated by environmental conditions.

Activation of natural killer (NK) cells in vivo with H-2 and non-H-2 alloantigens

Intraperitoneal inoculation of allogeneic lymphoid cells rapidly activates cytotoxic cells in the peritoneum which are nonadherent and express the NK-1, asialo-GM1, and Thy-1 antigens. Allogeneic spleen cells were very efficient at activating these natural killer (NK) cells, while allogeneic thymocytes were much less effective. Heat-killed allogeneic cells or sonicates also could augment NK activity.--Incompatbility at H-2K, H-2T-A, or H-2D readily evoked NK cell activity, while H-2S- and H-2I-E/C-associated a disparities did not. Non-H-2 differences also stimulated NK activity and augmentation was particularly evident in the Mls-disparate combinations. Thus, the same alloantigens which efficiently activate T cells also activate NK cells.

Neonatal tolerance of H-2 alloantigens. II. I region dependence of tolerance expressed to K and D antigens

Third-party skin allografts were employed to test the specificity of transplantation tolerance achieved by neonatal inoculation of cells bearing H-2 alloantigens. Tolerant animals rejected with normal vigour third-party grafts expressing strong Class I alloantigens foreign to the host and to the donor of the tolerance-conferring inoculum. However, these animals rejected with exceptional vigour third-party grafts expressing weak Class II alloantigens plus the tolerated Class I alloantigen; even third-party grafts comprised of the host's own Class II antigens in conjunction with the tolerated Class I alloantigen were acutely rejected. It is proposed, but there is no direct evidence to prove, that rejection of these third-party grafts is mediated by killer T cells directed at the tolerated Class I alloantigens and that these cells are activated by the presentation of the putative tolerogen in an inappropriate I region context. Inconsistency of these data with a clonal deletion mechanism is discussed.