172 Annual AACHT Meeting, 1985

INFLUENCE OF PRETRANSPLANT DONOR-SPECIFIC BLOOD TRANSFUSIONS ON MLC RESPONSIVENESS. Fred Sanfilippo, John Crawford, Gregory Ness, and Steven Geier; Durham, NC

Reciprocal one-way MLC testing was performed before and after donor-specific transfusion (DST) between one-haplotype identical family members being con- sidered for renal transplantation. Of all 55 patients entering the protocol betwe~:n 3/81 and 11/85, only eight (15%) were humorally sensitized following transfusion (as defined by a positive lymphocyte cross-match), and 43 of the remaining q- were transplanted, with only four graft failures to date. The mean MLC stimu- lation index (SI) of cells from potential recipients against donor cells was not different prior to DST comparing those patients who were: (1) subsequently sensitized; (2) not sensitized and not transplanted; (3) not sensitized and trans- planted with good outcome; and (4) not sensitized, transplanted with graft failure. Similarly, there was no significant change in donor-specific MLC reacnvlty for the entire unsensitized group comparing pre- (SI = 10.3 - 1.5) to post- ~SI 10.6 + 1.8) DST MLC reactions. In terms of responsiveness to pooled control cells, however, the unsensitized group showed a modest decrease m MLC stim- ulation following DST (SI = 35.5 -+ 4.5 vs. 26.8 +_ 3.3), as well as a decrease in PHA responsiveness. In comparison, patients who were sensitized following DST showed a marked increase in both donor-specific MLC stimulation (SI : 12.1 + 2.6 vs. 51.6 ~ 2t .3) as well as responsiveness to control cells ~SI ~: 47.1 - 24.0 vs. 91.6 - 51.81 and PHA. No significant changes in pre- vs. post- DST levels of MLC reactivity were seen in those patients who were transplanted and had irreversible graft rejection. Use of azathioprine with DST ~n - 20 patients) did not affect sensitization rates or pre- and post-transfusion MLC re- sponses. These findings suggest that: (1) the level of MLC reactivity to donor or control cells prior to DST does not predict patient sensitization or the likelihood of ultimate graft failure: (2) patients who develop humoral sensitization following DST show increases in both donor-specific and third-party MLC stimulation; and (3) patients who are not sensitized serologically by DST show no change in donor~ specific reactiwty and a mild decrease in control responses. These findings support the concept that DST may act: (1) by negative selection to identify patients who develop significant cellular as well as humoral responses to donor alloantigens: and possibly ¢2) reducing alloreactivity in patients who are not humorally sen- sitized by DST.

PREVENTION OF GRAFT VS. HOST DISEASE (GVHD) BY T CELL DEPLETION OF DONOR MARROW MAY IMPAIR THE GRAFT VS. LEUKEMIA (GVL) EFFECT. J.S. Thomp- son, R.C. Ash, M.S. Serwint, M. Cibull, Y. Maruyama, E. Romond, M. Doukas, M.E. Marshall, and J.S. Macdonald; Departments of Medicine, Pathology and Radiation Medicine, Universi(y of Kentuck,~ and Veterans Administration Medical Center, Lexington, KY

Two murine monoclonal antibodies (MOAb) have been developed to human T lymphocytes: T10B9 is an i gM MOAb that is cytotoxic in vitro with T tympho- cytes bearing the CD3 molecule in the presence of either rabbit or human com- plement; T12A10 is also an IgM that lyses CD6 bearing T iymphocytes with rabbit but not human complement. TIOB9 recognizes primarily medullary thy- mocytes while T12A10 reacts with both cortical and medullary cells; Either agent alone is effective for removing 9 7 - 9 9 % of T lymphocytes in vitro but neither alone is fully capable of tysing all PHA responsive T lymphocytes. Lysis is most effective when both are mixed as a cocktail. The effectiveness o f T celt depletion corresponded very closely with reduction in acute G V H D ; whereas G V H D occurred in 12/17 (70.5%) of patients receiving non-T cell depleted HLA-iden- tical marrow, the frequency was reduced to 2/9 ( 2 2 . 2 % ) w h e n T cells were

Abstracts 173

removed with T10B9 alone and to 0/20 when both T10B9 and T12A10 were combined to T cell deplete the inoculum. Failure to engraft and/or graft rejection was overcome by increasing TBI to 1400R and avoiding positively cross-matched marrow donors. With this regime, disease-free survival of low-risk patients (first remission ANLL/ALL, chronic phase CML, second remission or partial remission ANLL) has been 9/14 (64.3%). To the contrary, although G V H D has not been the primary cause of death, only 1/16 high-risk patients with blast crises CML or ANLL are alive and disease-free. Thus, G V H D has been effectively eliminated by the use of a cocktail of MoAb to deplete T cells in HLA-identical marrow but at the possible expense of loss of GVL effect.

CHARACTERIZATION OF LYMPHOCYTES OBTAINED FROM REJECTED KIDNEYS FOLLOWING ALLOGRAFT NEPHRECTOMY. A. Nikaein, R. Landesberg, K. McQueen, D. Ryan, and R. Insel; University of Rochester, Rochester, NY

Although the exact mechanism of the immune response to renal allografts is unknown, local infiltration by large numbers of lymphocytes indicates that these cells play a major role. Recently, studies by others using expanded T cells obtained from renal allograft needle biopsies have shown proliferation of both donor class II-specific PLT (primed lymphocyte test) and class I-specific cytotoxic T cells. In our current studies, cells were obtained from rejected kidneys following allograft nephrectomy. We compared these renal allograft mononuclear (RAM) cells with peripheral blood mononuclear (PBM) cells obtained simultaneously from each patient. The recovered cells were tested for their phenotype, immunoglobulin production, cell mediated lympholysis, and natural killer activities, as well as their ability to undergo secondary proliferation following allorecognition in primed lymphocyte testing (PLT). Compared to autologous PBM cells, the RAM cells had a different proport ion of lymphocyte subsets. Furthermore, a significant increase in immunoglobulin-producing B cells was found. However , neither do- nor-specific class I cytotoxic T cell nor natural killer activity was observed in these assays. The PLT assay of these patients have been variable and showed reactivity toward autologous HLA-DR 7 associated with DQw3. This reactivity may have been related to an active infection with cytomegalovirus, recognition of donor HLA-DR antigen, or absence of PLT activity.

These findings suggest that the nature of immune rejection varies in different patients. The study of lymphocytes obtained from the kidneys following allograft nephrectomy provides a unique opportunity to examine the immunologic mech- anism in renal allograft rejection.

IN VITRO OBSERVATIONS OF FAULTY IMMUNOREGULATION IN SECONDARY ABORTING WOMEN. Donald S. Torry, John A. Mclntyre, Fritz E. Lower, and Peter R. Mc- Connachie; Departments of Medical Microbiology and Immunology and Obstetrics and Gynecology. South- ern Illinois University School of Medicine, Spring/ield, IL

Studies have shown that two groups of spontaneous aborting women exist: pri- mary (1 ° ) and secondary (2°). Obstetrical histories of 2 ° aborters show they often have had viable births or stillbirths prior to their recurrent abortions. Immu- nological studies have shown 2 ° aborter sera contain both complement-dependent (CDC) and complement- independent (ADCC) antipaternal lymphocytotoxins. However , sera reactivity of 2 ° aborters have the characteristic of not being re- stricted to paternal HLA phenotypes. 2 ° aborters produce antibodies reactive