Clonal analysis of the lymphoid cells mediating skin allograft rejection. Mediation of graft rejection in vivo by cloned Lyt-1+2- proliferative, noncytotoxic long-term cell lines

Induction of allograft tolerance to the H-Y antigen in adult C57BL/6 mice: differential effects on delayed-type hypersensitivity and cytolytic T-lymphocyte activity

This study describes the induction of allograft tolerance to the "male-specific," minor histocompatibility antigen, H-Y, in adult C57BL/6 female mice, and the effects of this tolerance induction on two immune parameters associated with graft rejection: delayed-type hypersensitivity (DTH) and cytolytic T-lymphocytes (CTL). B6 females tolerized to H-Y, by a single iv injection of C57BL/6 male lymphocytes, exhibited prolonged or permanent survival of B6 male tail skin grafts. Graft-induced DTH against H-Y antigen was reduced or abrogated in tolerized females. Delayed onset of graft rejection in partially tolerant females correlated with delayed onset of DTH, and eventual rejection of grafts was accompanied by an increase in H-Y-specific DTH. In contrast, H-Y-specific CTL activity was not consistent with graft status. These data demonstrate a correlation between H-Y-specific DTH and rejection of male skin grafts by B6 female mice and are most consistent with a major effector role for DTH in chronic graft rejection.

Suppression of experimental autoimmune diseases and prolongation of allograft survival by treatment of animals with low doses of heparins

The ability of activated T lymphocytes to penetrate the extracellular matrix and migrate to target tissues was found to be related to expression of a heparanase enzyme (Naparstek, Y., I. R. Cohen, Z. Fuks, and I. Vlodavsky. 1984. Nature (Lond.). 310:241-243; Savion, N., Z. Fuks, and I. Vlodavsky. 1984. J. Cell. Physiol. 118:169-176; Fridman, R., O. Lider, Y. Naparstek, Z. Fuks, I. Vlodavsky, and I. R. Cohen. 1987. J. Cell. Physiol. 130:85-92; Lider, O., J. Mekori, I. Vlodavsky, E. Baharav, Y. Naparstek, and I. R. Cohen, manuscript submitted for publication). We found previously that heparin molecules inhibited expression of T lymphocyte heparanase activity in vitro and in vivo, and administration of a low dose of heparin in mice inhibited lymphocyte traffic and delayed-type hypersensitivity reactions (Lider, O., J. Mekori, I. Vlodavsky, E. Baharav, Y. Naparstek, and I. R. Cohen, manuscript submitted for publication). We now report that treatment with commercial or chemically modified heparins at relatively low doses once daily (5 micrograms for mice and 20 micrograms for rats) led to inhibition of allograft rejection and the experimental autoimmune diseases adjuvant arthritis and experimental autoimmune encephalomyelitis. Higher doses of the heparins were less effective. The ability of chemically modified heparins to inhibit these immune reactions was associated with their ability to inhibit expression of T lymphocyte heparanase. There was no relationship to anticoagulant activity. Thus heparins devoid of anticoagulant activity can be effective in regulating immune reactions when used at appropriate doses.

Transforming growth factor-beta inhibits the in vitro generation of lymphokine-activated killer cells and cytotoxic T cells

The effect(s) of purified transforming growth factor-beta (TGF-beta) and platelet-derived growth factor (PDGF) on the induction and function of lymphokine-activated killer (LAK) cells and cytotoxic T lymphocytes (CTL) was examined. The addition of TGF-beta, but not PDGF, to cultures containing fresh C57BL/6 mouse splenocytes or human peripheral blood lymphocytes plus recombinant interleukin-2 markedly inhibited the development of mouse and human LAK cell activity (measured after 3 days for cytotoxicity against cultured or fresh tumor targets in 4-h 51Cr release assays). The addition of TGF-beta, but not PDGF, to a one-way, C57BL/6 anti-DBA/2, mixed lymphocyte reaction effectively blocked the generation of allospecific CTL as well. However, TGF-beta did not inhibit the effector function of LAK cells or of allospecific CTL when added directly to the short-term cytolytic assay. A second form of homodimeric TGF-beta, type 2, was also found to be suppressive on the development of murine LAK cells and allospecific CTL. Collectively, these data demonstrate that the peptide TGF-beta is a potent inhibitor of LAK cell and CTL generation in vitro.

Functional characterization of infiltrating T lymphocytes in human hepatic allografts

We have employed recently developed techniques in T-cell culturing to study the nature and function of infiltrating hepatic allograft T cells. Using the rationale that intragraft T cells are activated during cell mediated damage to the allograft, we were able to show that these cells would propagate and remain functionally active in the presence of the T-cell growth factor, IL-2. In several instances, phenotypic analysis of cells grown in this manner was very similar to that found within the graft. Both proliferative and cytotoxic responses could be detected from the cultured cell lines. The majority of the proliferative responses were donor-directed and immunogenetic analysis could define donor-directed HLA reactivity, to either class I or class II antigens, or both. Monoclonal anti-HLA antibodies inhibition profiles verified the apparent HLA reactivity. In a smaller percentage of cases, only IL-2 responsiveness could be detected, and no HLA reactivity could be determined. Cytotoxicity could be detected against both class I and class II antigens, however, those cells which demonstrated a greater magnitude of donor-directed cytotoxicity appeared to be directed against class I antigens. A significant correlation between donor-directed proliferation of biopsy cultured lymphocytes and cellular rejection was found. This model appears to be useful in delineating functions of the intragraft T-cell population during rejection.

Genetic and stimulatory cell type requirements for inducing class I major histocompatibility complex alloantigen-specific in vivo cytotoxic T cell immunity

Current interpretation based on analytical in vitro works that actions of Ia antigens and accessory cells such as macrophages and dendritic cells are crucial for inducing cytotoxic T cell responses to class I major histocompatibility complex (MHC) alloantigens has been challenged by experiments performed in a newly developed system handling in vivo cytotoxic T cell immunity. We first characterized the transplantation immunity for second-set rejection of ascitic tumor allografts as principally induced by allogeneic stimulator cells via direct pathway, and as exclusively mediated by class I MHC alloantigen-specific in vivo cytotoxic T cell activity. By comparison of activities of limiting effective doses (10(4)-10(5) cells per mouse) of various stimulator cells in this defined system, we could demonstrate that genetic disparity at the D region of H-2 to the recipient is just enough for inducing the immunity, and presence of allogeneic or syngeneic Ia antigens in addition to H-2D alloantigens on stimulator cells does not give any premium effect. Further study revealed that allogeneic peritoneal cells rich in macrophages or glass-adherent spleen cells enriched for dendritic cells are not stronger stimulators than allogeneic adherent cell-depleted spleen cells and semi-allogeneic thymocytes. These results fit with the alternative concept that the physiological pathway inducing in vivo cytotoxic T cell immunity for graft rejection entirely depends on class I MHC antigens on live lymphocytes as self-supported stimulators, and does not crucially involve additional stimulator activities of Ia antigens and special accessory cell types, which must be in vivo concerned with induction of other types of transplantation immunity.

Enucleation-induced metastasis of intraocular melanomas in mice

The present review summarizes and integrates the results from recent studies on the metastatic behavior and immunology of intraocular melanomas in mice. The data suggest strongly that enucleation of a melanoma-containing eye promotes intravascular showering of melanoma emboli that, in the immunologically compromised host, develop into fulminant metastases. By contrast, similarly disseminated melanoma cells are rejected by T-cell-dependent immune mechanisms in the immunocompetent host. Preliminary results suggest that this immune rejection is mediated by cytotoxic T-lymphocytes. Several independent experiments showed that neither enucleation nor immune impairment alone is capable of inducing progressive metastases in the intraocular melanoma-bearing host. Thus, the development of progressive metastases from intraocular melanomas is a two step process requiring: (1) a surgery-induced, intravascular showering of melanoma emboli and (2) a simultaneous impairment of T-cell-dependent immune functions. The present results support the Zimmerman-McLean hypothesis that enucleation of a melanoma-containing eye can (under defined conditions) promote the metastatic spread of the primary tumor. The finding that immunocompetent intraocular melanoma-bearing hosts reject disseminated metastases offers hope that immunotherapeutic maneuvers may greatly reduce the risk of metastatic disease.

Biological activity of recombinant human interleukin-2 produced in Escherichia coli

The gene for interleukin-2 was isolated from the Jurkat cell line and from normal peripheral blood lymphocytes and, when inserted in Escherichia coli, was expressed at high concentrations. This interleukin-2 was purified to apparent homogeneity and tested for biological activity in a variety of assays in vitro and in vivo. The recombinant lymphokine supports the growth of murine and human interleukin-2 dependent cell lines, enhances the generation of murine and human cytolytic cells in vitro, and generates lymphokine activated killer cells from murine and human lymphocytes. It has a serum half-life of 2 to 3 minutes in the mouse and significantly enhances the generation of cytolytic cells in vivo after alloimmunization. No functional differences between native and the recombinant interleukin-2 molecules have been detected.

Cloned LYT-2+ cytolytic T lymphocytes destroy allogeneic tissue in vivo

The long-accepted notion that alloimmune cytolytic T cells (CTL) mediate transplantation immunity has recently been called into question. In order to ascertain directly whether alloimmune CTL can mediate destruction of foreign tissue, we tested the ability of mouse CTL expanded as cloned populations in vitro to destroy allogeneic skin in vivo. The results of these studies prove unequivocally that cloned Lyt-2+ CTL can perform this task in an immunologically specific, H-2-restricted, and dose-dependent fashion.