"Self-reactive" T cells. II. Transferred syngeneic lymphoblasts induce T "stimulator" cells in vivo, to which syngeneic T cells "respond" in a syngeneic MLC in vitro

Immune response: tissue specific T-lymphocytes

The lymphatic system forms a 'blind' plexus of vessels that in general are found in tissue which has an inherently high replicative capacity. It is this system that is responsible for the rapid deployment and circulation of tissue-specific T-lymphocytes for the inspection of cell-surface aberrations within the tissue. The presence of tissue-specific T-lymphocytes explains why 90% of lymphocytes are found outside the lymphatic system and why they migrate in a selective manner. The tissue-specific T-lymphocyte is considered to express a common lymphocyte cell surface pattern, the homotype, and a tissue-specific cell-surface pattern, the histotype which may involve MHCA and mHCA. It is the histotypic pattern that is responsible for the tissue specificity of the tissue-specific T-lymphocyte. The presence of tissue-specific T-lymphocytes does pose problems for the immune system. If different tissue-specific T-lymphocytes met within a particular tissue, 'lost' lymphocytes, an immune response will be generated against the intruder (lost lymphocyte), and the intruder will not be able to recruit other immunocompetent cells in that tissue. This immune reaction is an attempt to change the histotypic pattern of the intruder. This situation would explain the autologous immune response. This response however is suppressed in the systemic system by immunosuppressive compounds from the liver. It is only in the tissues that the tissue-specific T-lymphocytes are released from this suppression, in order to initiate immune reactions against aberrant cell-surface patterns.

Lymphoblastogenesis stimulates proliferation of interacting Lyt1 T cells in a syngeneic system

The intravenous transfer of polyclonally activated lymphoblasts elicited a proliferative response of host-derived Lyt1 T cells in the spleens of syngeneic recipient mice. These Lyt1 T cells (responding in vivo to a syngeneic lymphoblast graft) stimulated proliferation of resting, syngeneic splenic Lyt1 T cells, derived from uninjected mice, in a one-way syngeneic mixed lymphocyte culture in vitro. The data are discussed in the context of T cell activation induced by lymphoblastogenesis in a syngeneic system.

Self-reactive T cells. IV. Self-reactive T cells induce polyclonal differentiation of IgM-producing B cells in vivo and in vitro

Intravenous injection of lymphoblasts (generated in vitro by different T- or B-specific mitogens) induced a polyclonal activation of IgM-producing B cells in vivo in the spleens of syngeneic recipient mice. This polyclonal differentiation of host-derived B cells to IgM-producing plaque-forming cells was stimulated by host-derived self-reactive T cells activated in the splenic lymphoid cell population in response to the syngeneic lymphoblast graft. We found a stable factor in the supernatants of cultures of proliferating self-reactive T cells that induced (antigen-independent) polyclonal maturation, but not proliferation of IgM-producing B cells.

Self-reactive T cells. V. T cell-mediated suppression of B cell responsiveness to LPS

The intravenous injection of polyclonally activated lymphoblasts elicited a proliferative T cell reaction in the spleens of syngeneic recipient mice. In the non-fractionated cell populations obtained from these spleens 6 days after lymphoblast transfer, the LPS-induced proliferation and differentiation of B cells in vitro was suppressed. This suppressive effect was mediated by T cells, as i) treatment with anti-Thy-1 antiserum plus complement restored responsiveness of B cells to LPS in the spleen cell population that had responded in vivo to a syngeneic lymphoblast graft, and ii) the responsiveness of B cells to LPS was not impaired in non-fractionated spleen cell populations of nu/nu mice injected with syngeneic lymphoblasts. The relationship of this nonspecific T suppressor cell activity to the previously described non-specific T helper cell activity for B cell activation is discussed.