William L. Elkins

Pathogenesis of a Local Graft versus Host Reaction: Immunogenicity of Circulating Host Leukocytes

A local invasive-destructive reaction typical of that seen in allograft rejection occurs when Lewis rat spleen cells are inoculated under the capsule of Lewis kidney freshly grafted into F1 hybrid hosts. Thus the donor lymphoid cells can be immunogenically stimulated by circulating host leukocytes and the interaction of these two cell populations results in nonspecific damage to kidney parenchyma. The results indicate that passenger leukocytes in organ allografts may be important immunogenic agents.

IDENTIFICATION OF A SINGLE STRONG HISTOCOMPATIBILITY LOCUS IN THE RAT BY NORMAL SPLEEN‐CELL TRANSFER*

When adequate doses of immunologically competent cells are transferred from an adult donor into a host that possesses foreign, individual-specific antigens, these cells usually become immunologically activated and attack the host. This phenomenon is descriptively called a graft-versus-host reaction (GVHR). The factors which influence the pathogenesis of such reactions are multiple and varied; however, experiments can be designed in which the most important variable influencing the intensity of the GVHR is antigenic disparity. For this reason, the GVHR can be utilized to evaluate the degree of histoincompatibility existing between various members of a species. At present, the clearest application of this principle is the demonstration by Brent and Medawar that the intensity of local cutaneous inflammatory lesions in a panel of prospective donor guinea pigs, following the injection of lymphoid cells from a prospective recipient, correctly predicted the order with which the latter rejected skin grafts from members of that panel.’ Unfortunately, little is known about the antigens responsible for the elicitation of GVHR’s. It is generally assumed that the histocompatibility factors recognized in the GVHR are those involved in the rejection of a foreign skin, tumor, or organ graft by the host. However, pertinent evidence on this point has been derived from only two species, the chicken and the mouse. In both species, it is known that many histocompatibility (H) loci exist, but apparently only the products of a single locus in each case are sufficiently immunogenic to elicit a GVHR when moderate doses of lymphoid cells from normal (i.e., unsensitized) donors are employed. Because of these findings, Simonsen has suggested that techniques involving the induction of GVHR’s by normal lymphocyte transfer (NLT) might be utilized to test 2-8

Cellular control of lymphocytes initiating graft vs. host reactions

Abstract Spleen and lymph nodes of rats, in which a state of transplantation tolerance has been deliberately abolished by adoptive transfer, contain cells which can inhibit syngeneic lymphocytes from normal donors in the initiation of a graft versus host reaction. The suppressive effect shows immunologic specificity. Suppressor cells were not detected in tolerant chimeras.

The use of cytotoxic T cell lines to detect the segregation of a human minor alloantigen within families

A cytotoxic T cell (CTL) line, which detected a minor alloantigen provisionally called W was generated in vitro with lymphocytes from a multiply transfused individual, S1. Lymphocytes from S1 were first stimulated with cells from an unrelated known from previous studies to express the minor antigen. The primary CTL were then restimulated with cells from a W +/ve HLA identical sib, S2, in the presence of IL-2. As in previous work, recognition of the W antigen by these CTL was restricted by HLA-B7. Antigen assignments of W + W -, based upon cold target inhibition studies, confirmed previous assignments which had depended upon the ability of lymphocytes either to stimulate the generation of or to be killed by anti-W CTL effectors. Testing of lymphocyte targets from members of several unrelated families in which HLA-B7 segregated showed that the CTL lines could detect the expression of W on cells of individuals in the general population. In 3 of 5 cases, members of an HLA identical sib pair differed for W. These results open up the possibility of designing studies using CTL lines to determine whether differences for minor alloantigens play a role in clinical transplantation.

Cytotoxic T lymphocyte lines (CTLL) against a human minor alloantigen

Cytotoxic T-cell lines were generated following in vitro culture of lymphocytes from a patient suffering from aplastic anemia together with those of his HLA-identical brother, a repeated transfusion donor. The segregation pattern within the family of the determinant(s) detected by these cytotoxic cells strongly suggested that a minor alloantigen(s) was being detected. Testing of the effectors on a panel of unrelated individuals indicated that it was best seen in association with HLA-B7, which was common to both the patient and his sibling donor.

Partial tolerance and immunity after adoptive abrogation of transplantation tolerance in the rat

Abstract Lewis rats were rendered hematopoietic and lymphoid cell chimeras by injection of (LBN)F 1 hybrid cells at birth or following treatment with cyclophosphamide in adult life. The establishment of transplantation tolerance was indicated by acceptance of (LBN)F 1 skin grafts and specific unresponsiveness in graft vs. host reaction (GvHR) and mixed lymphocyte interaction (MLI) in vitro . Tolerance was abolished by adoptively transferred Lewis lymphocytes, and the loss of chimerism and recovery of specific reactivity by blood lymphocytes were monitored independently by mixed lymphocyte cultures. Recovery of competence to initiate GvHR by splenic and lymph node cells was monitored by the local renal graft vs. host technique. Both techniques measure essentially the proliferative response of certain lymphocytes to foreign cellular AgB antigens, and both detected a prolonged, but gradually weakening, state of partial tolerance to the AgB factors to which tolerance had originally been induced. During this phase of partial tolerance the former chimera rejects skin and lymph node cell grafts from (LBN)F 1 donors with alacrity, but in some cases accepts (LBN)F 1 kidney grafts. Cytotoxic antibodies appear in the serum soon after allogeneic chimerism is terminated. These results are interpreted to indicate that a state of partial tolerance exists among the cells which proliferate in response to certain AgB antigens in GvHR and MLI in the formerly tolerant chimera, and that a state of transplantation immunity (possibly to other determinants) coexists with this partial tolerance.

Synergistic interaction of h-y and h-2k in elicitation of graft-versus-host response.

Lymph node cells from female bm-1 donors induced greater mortality among male than female (bm-1 b)F1 hosts which had previously been sublethally irradiated. The same effect was not seen when wild type (b) parental donor cells were injected, nor in other combinations involving H-2K mutant C57BL/6 mice. The selective mortality encountered among male hosts in receipt of bm-1 female cells was shown to depend upon recognition of H-Y in the recipient, because this sex effect disappeared if the donors were first rendered tolerant of H-Y. However, absence of graft-versus-host (GVH) mortality with other combinations indicated that recognition of H-Y alone was not sufficient. When cells from donors tolerant of H-Y were mixed with cells from donors tolerant of H-2Kb, enhanced mortality among male F1 hosts was again observed. We interpret the results to indicate that there is a synergistic interaction of donor lymphocytes which recognize H-Y and H-2Kb during the GVH response.

Variable effect of anH-21 barrier on response to skin allografts in the mouse

Abstract(AQR×B10)F1 mice were grafted with skin from donors differing in theK, I, KI, andISD regions of theH-2 complex. A dichotomy was observed in the fate of theH-2I-disparate grafts: either they were rejected acutely within the second week or were accepted indefinitely. Acceptances were much more common among male than female hosts. Acceptor status was limited to the I group, was unpredictable in occurrence, was not well-correlated with positive serum anti-Ia titers, and did not confer protection of grafts that were alike atH-2I but different atH-2K orH-2D. Since theH-2I barrier studied here elicited such divergent responses in genetically identical hosts, it is unlikely that any histocompatibility typing test could predict graft fate.