Studies on the mitogen responses of germfree allogeneic chimeras. II. Maturation of two cell types and partial restoration of responsiveness of the short-term chimeras

Germfree allogeneic bone marrow chimeras (ABMC) were produced by the i.v. injection of approximately 10(7) bone marrow cells from germfree DBA/2 mice into lethally irradiated germfree C3H mice. In the germfree state, the short-term ABMC showed no histologic signs of graft-vs-host reactions (GVHR), yet splenic lymphocytes were unable to respond to PHA, Con A, or SRBC. Attempts to remove responsiveness by the implantation of a DBA/2 thymus under the host kidney capsule also resulted in failure. However, when the donor thymus was enclosed in a cell-impermeable chamber to eliminate a GVH reaction, responsiveness to Con A was restored. The PHA and SRBC responses were unaffected by this treatment. Daily injections of thymosin caused both an increased Con A response and increased numbers of PFC, although the PHA response was again unaffected. Thus, soluble substances from thymic tissue can be used to overcome partially the histocompatibility barrier present in the ABMC that affects at least two different functional cell populations.

Effect of age on T cell differentiation

A brief overview of the area of T cell aging is presented by first discussing the age-related changes in T cell activities, and then by focusing attention on the possible mechanisms that may be responsible for the decline. Present evidence indicates that thymic involution precedes and therefore may be responsible for the age-dependent decline in the ability of the immune system to generate functional T cells. At this time, it appears that the primary effect of thymic involution is on a T cell differentiation pathway affecting the more mature T cells first with time, and then the less mature T cells. Thus, the thymus may be the aging clock for the immune system. Further studies should be centered around processes regulating growth and atrophy of the thymus.

Sclerodermatous graft-versus-host disease limited to an area of measles exanthem

A female patient with severe idiopathic aplastic anaemia received a successful bone-marrow transplant from her HLA-identical, mixed-lymphocyte-culture-compatible, brother. 8 months after transplantation she had localised cutaneous measles. Chronic sclerodermatous changes developed which were indistinguishable from chronic graft-versus-host disease and were limited to the areas of the original exanthem. Interaction between viral infection and minor histocompatibility differences probably resulted in graft-versus-host disease in this patient.

A solution to the graft-versus-host problem in bone marrow transplantation to humans

Many clinical situations arise where it would be desirable to transplant bone marrow to a marrow function deficient patient. However, bone marrow is immunologically competent by virtue of its content of lymphocyte precursors. Marrow transplantation in these patients is followed by the graft's immunological rejection of the patient - a fatal disease. A system for specific abrogation of this graft-versus-host disease after xenogeneic bone marrow transplantation to humans is presented. In this system, prospective patient cells are removed by skin biopsy for example, and injected into a fetal chimpanzee. The fetal chimpanzee becomes tolerant to this patient's antigens and will not attack or reject them when its bone marrow is removed after birth and injected into the specific patient from whom the tolerogenic cells were obtained. A simple and straightforward experimental test of this system's clinical applicability is also presented.

Tumor induction in host-versus-graft disease. I. Clinical and pathologic features

Perinatal C57BL/1 mice given injections of (SJL/J X C57BL/1)F1 spleen cells developed a highly lethal runting syndrome, designated host-versus-graft disease (HVGD). The mortality was related to the dosage of F1 cells. Acute pathologic changes resembled those occurring in parent leads to F1 graft-versus-host disease (GVHD), except for more pronounced plasmacytosis. Mice suffering from HVGD recovered clinically with no sequelae except for a slight increase in the incidence of lymphomas over control mice. Such mice were hyperreactive to F1 cells utilized to initiate the original HVGD syndrome. Most of the tumors developed in those animals receiving the initial injection of F1 spleen cells within 24 hours of birth. Tumor incidence was unrelated to the clinical severity of HVGD. By contrast, GVHD in the same strain combination resulted in a much higher incidence of lymphomas in a much shorter time. Parental strain cells were detectable in the F1 hosts up to the time of tumor development. HVGD has a low tumor induction potential; GVHD has a high tumor induction potential.

Toxic epidermal necrolysis from graft-vs-host disease. Occurrence in a patient with thymic hypoplasia

An infant with diarrhea, failure to thrive, and a seborrhea-like skin eruption was thought to have fatal familial Leiner's syndrome. Treatment with nonirradiated plasma was followed by graft-vs-host disease and fatal toxic epidermal necrolysis; thymic hypoplasia was found at autopsy. Accurate diagnosis of immunodeficiency syndromes is essential to avoid potentially harmful therapy.

Effects of restoring lethally irradiated mice with anti-Thy 1.2-treated bone marrow: graft-vs-host, host-vs-graft, and mitogen reactivity

In vitro treatment of A/J mouse bone marrow with anti-Thy 1.2 serum and guinea pig complement (GPC) eliminated its ability to induce graft-vs-host (GVH) mortality in lethally irradiated C57BL/6J x A/F1 (BAF1) mice. The anti-Thy 1.2 and GPC treatment of A/J marrow significantly reduced spleen cell activation by phytohemagglutinin (PHA) but not lipopolysaccharide (LPS) stimulation in A/J mice assayed 6 weeks after lethal irradiation and reconstitution with the treated marrow. However, the anti-Thy 1.2 treatment of A/J bone marrow did not impair the ability of the lethally irradiated, reconstituted, syngeneic mice to reject C57BL/6J skin grafts. We conclude that lymphocytes in bone marrow which are susceptible to inactivation by anti-Thy 1.2 mediate allograft reactions and/or that radioresistant cells which persist in the recipient initiate rejection of allogeneic skin grafts.

Evidence for two types of non-specific suppressor cells activated by the graft-versus-host reaction in mice

In vitro experiments were carried out to investigate the immunosuppressive efect of different populations of spleen cells obtained from animal experiencing a graft-versus-host reaction (GVHR). To induce the GVHR, parental lymphoid cells were injected into adult F1 hybrid mice. GVHR-activated spleen cells (GVH-sc) taken at different times post-GVHR induction were separated into adherent and non-adherent fractions and treated with anti-theta serum plus complement. The different types of GVH-SC were added to either parental (donor-type) of F1 (host-type) normal spleen cells and cultured with sheep erythrocytes in a modified Marbrook chamber. It was found that both adherent and non-adherent 10-day GVH-SC significantly inhibited the plaque-forming cell response of F1 normal spleen cells but not that of parental normal spleen cells. Significant suppression of the parental response was observed following the addition of 15-day GVH-SC or anti-theta treated adherent and non-adherent 7-day GVH-SC. The results suggest that the non-specific immunosuppressive effect of GVH-SC is mediated by GVHR-activated macrophages and B lymphocytes found in the anti-theta treated adherent and non-adherent fractions of the GVH-SC suspensions respectively.

Subpopulations of mouse T lymphocytes. II. Suppression of graft-vs.-host reactions by naturally proliferating splenic T cells

The immunological role of a naturally proliferating subpopulation of splenic T cells was investigated using the graft-vs.-host (GvH) reaction on the mouse. Normal parental spleen cells, purified splenic T cells or lymph node cells were pulse-treated for one hour in vitro with tritiated thymidine of high specific activity ([3H]dThd, "thymidine suicide"). The treatment specifically and selectively kills proliferating cells which are actively synthesizing DNA, i.e. cells in S phase. Following treatment, the cells were transferred to F1 recipients and the GvH reaction measured by the splenomegaly assay. The results showed that the GvH effector cells in the donor spleen and lymph node are nonproliferating T cells. Furthermore, donor spleen cells treated with [3H]dThd consistently had enhanced GvH reactivity when compared to the controls, while the phytohemagglutinin response of these same treated cell suspensions was significantly inhibited. When purified splenic T cells were used, treatment with [3H]dThd also caused an increase in the GvH reaction, showing that a T cell population was being affected by the cycleactive agent. These results indicated that some naturally proliferating T cells have suppressor functions, and their specific inactivation allows nonproliferating effector T cells to mount a more vigourous GvH reaction.