THE REACTION OF IMMUNOLOGICALLY ACTIVATED LYMPHOID CELLS AGAINST HOMOLOGOUS LYMPHOID CELLS AGAINST HOMOLOGOUS TARGET TISSUE CELLS IN VITRO

The effect of heterologous anti-lymphocyte seerum on mouse hemopoietic stem cells

The present study has demonstrated that rabbit anti-mouse lymphocyte serum (RAMLS) has the capability of destroying bone marrow cells and suppressing hemopoietic stem cell function. The in vitro incubation of bone marrow suspensions with RAMLS caused extensive cell lysis with an apparent preferential destruction of lymphoid, erythroid, and blastoid elements. Using the spleen colony assay, the number of functional hemopoietic stem cells was found to be markedly reduced in bone marrow populations exposed to RAMLS in vitro. Further, this loss of stem cell function could be produced by exposing marrow suspensions to small concentrations of antiserum which did not produce detectable cytotoxic effects on the general marrow population. A similar effect of RAMLS upon hemopoietic stem cells was found in vivo. The intravenous injection of RAMLS into lethally irradiated mice immediately after the infusion of isogeneic marrow cells reduced the number of spleen colonies formed, indicating that the antiserum could exhibit a deleterious effect upon stem cells in the bloodstream of the intact animal. Normal animals treated with daily subcutaneous injections of RAMLS for 3 wk had a significantly reduced marrow content of functional hemopoietic stem cells, suggesting that RAMLS can affect stem cells located in situ in the bone marrow. The experiments indicate that RAMLS possesses potential marrow toxicity.

Renal homotransplantation in rats. I. Allogeneic recipients

Within 3-6 hr after the reestablishment of the circulation, a characteristic pathology developed in renal homotransplants. Blood monocytes and lymphocytes adhered to large thin-walled vessels of the septa carrying interlobular arteries, traversed their walls, and aggregated in the connective tissue spaces around them. Within 3 days, the number and size of the extravascular cells markedly increased, filling the septa completely and spreading from them centrifugally to occupy the intertubular spaces throughout the cortex. The composition of these aggregates at first was a mixture of lymphocytes and monocytes, and later consisted of large blast cells, macrophages, a few plasma cells, and polymorphonuclear leukocytes. Mitotic activity was seen 2 days after surgery among the large blast cells and increased to a maximal level a day later. Coevally with these changes, the thin-walled septal vessels, intertubular veins and capillaries, and finally, arteries and arterioles, in that order, were damaged. Focal injury of tubules was slight 24 hr after homografting; widespread cortical necrosis had developed 5-7 days later. At no time up to 7 days were concentrations of immunoglobulins detected by fluorescence microscopy in the transplanted kidneys. The morphologic manifestations and temporal sequences of renal homograft destruction suggested that several mechanisms acted synergistically to eliminate the transplant. The initial injury appeared to be the result of an interaction between host lymphoid cells and target endothelium, a phenomenon akin to allogeneic inhibition; followed by spreading ischemia; additional contact injury to tubules; and nonspecific inflammation associated with necrobiotic tissue.

Cytotoxicity by nonimmune allogeneic lymphoid cells. Specific suppression by antibody treatment of the lymphoid cells

Nonimmune lymphoid cells were capable of causing cytotoxicity of H-2 incompatible mouse tumor cells in vitro in the presence of PHA, whereas syngeneic cells were not. Semisyngeneic and X-irradiated (1500-3000 R) F(1) hybrid lymphoid cells were cytotoxic for target cells derived from one of the parental strains. In addition, parental nonimmune and X-irradiated lymphoid cells damaged hybrid target cells. It was concluded that one component of cytotoxicity was not related to an induction of a primary immune response in vitro, since F(1) hybrid cells are not capable of reacting immunologically against parental type target cells. It seemed probable that cytotoxicity was caused by target cell confrontation with antigenically and/or structurally incompatible lymphoid cells. This conclusion was strengthened by the demonstration that isoantibodies produced in the target strain and directed against the allogeneic lymphoid cells specifically suppressed cytotoxicity. Isoantibodies reacting against some but not all of the antigenic determinants of the lymphoid cells differentiating them from the target cells did not suppress cytotoxicity. The specific suppression of cytotoxicity by specific isoantibodies against the lymphoid cells support the allogeneic inhibition concept.

The interaction of donor and host lymphoid cells in the pathogenesis of renal cortical destruction induced by a local graft versus host reaction

The graft versus host reaction (GVHR), which results from the injection of parental strain spleen cells beneath the kidney capsule of F(1) hybrid rats, is transferable during its developmental phase into F(1) hybrid hosts isogeneic with the primary host, but not into secondary hosts of the parental (donor) strain. Furthermore, the GVHR propagates but rarely in secondary hybrid hosts which are allogeneic with respect to the primary hosts, but which are also genetically tolerant of donor-type cells. These findings indicate that the donor cells not only initiate the GVHR but also maintain it by virtue of immunologically specific activity. Whole-body irradiation of (LBf)F(1) and (LBN)F(1) hosts 24 hours prior to the injection of parental (L) spleen cells results in inhibition of the subsequent GVHR to a degree commensurate with the radiation damage sustained by the lymphoid system of the host. Furthermore, propagation of transferred GVHRs did not occur if susceptible secondary hybrid hosts had been previously irradiated. These findings indicate that radiosensitive host cells play a continuing and essential role in the pathogenesis of the invasive-destructive lesion. It is concluded that the development of this lesion depends upon the continuous interaction of the specifically reactive donor-type cells with an immunologically non-specific population of host mononuclears.

CONTACT-INDUCED CYTOTOXICITY BY LYMPHOID CELLS CONTAINING FOREIGN ISOANTIGENS

In tissue culture, immune lymph node cells containing foreign histocompatibility antigens of the H-2 type exert marked cytotoxic effects on tumor cells incompatible with the H-2 antigen. An equally pronounced effect is obtained when normal allogeneic and semi-isologous lymphoid cells of F(1) hybrids are caused to aggregate around the target tumor cells by treating the cultures with either heat-inactivated rabbit antiserum to mouse cells or phytohemagglutinin. Isologous lymph node cells have no effect. Thus, aggregation of lymphoid cells and target cells is a necessary but insufficient requirement for cytotoxicity in vitro; in addition, close contact must be established between histoincompatible cells.

HOMOGRAFT TARGET CELLS: SPECIFIC DESTRUCTION IN VITRO BY CONTACT INTERACTION WITH IMMUNE MACROPHAGES

Specific adherence and mutual immunologic destruction occurred after contact in vitro of immune peritoneal macrophages from C57BI/6K mice with homograft target cells from A/Jax mice. Cell destruction apparently resulted from a nonphagocytic mechanism involving cell contact rather than humoral antibody. Cell destruction was determined by a plaque technique with either immunecells or target cells as monolayers.