IDENTIFICATION OF LYMPHOCYTE-DEPENDENT ANTIBODY IN SERA FROM MULTIPLY TRANSFUSED PATIENTS

Abstract

Lymphocyte-dependent antibody (LDA) against allogeneic human cells was detected in the sera of eight multiply transfused patients. With use of rapid in vitro chromium release assays, LDA activity was detected against freshly explanted allogeneic lymphocytes and various tissue culture cell lines: Raji (a human lymphoid line), HeLa, and HML-1 (a melanoma line). Antibody activity was found in the 7S region after Sephadex G-200 fractionation and activity was blocked by antihuman IgG antisera. Comparison of LDA with complement-dependent antibody activity (CDA) revealed in each case antiserum concentrations at which LDA activity was detected in the absence of CDA activity. Persistence of LDA was demonstrated in one patient by high levels of antibody activity 1 year after the last transfusion. The effect of LDA on direct cell-mediated cytotoxicity was examined in one case by reacting cytotoxic human peripheral blood lymphocytes with LDA-coated and uncoated target cells. More target cell damage resulted in the presence of LDA, demonstrating that humoral antibody may augment rather than inhibit cytotoxicity with sensitized lymphocytes.