UTILITY OF PROTEASE-DIGESTED HUMAN PERIPHERAL BLOOD LYMPHOCYTES FOR THE DETECTION OF LYMPHOCYTE-REACTIVE ALLOANTIBODIES BY INDIRECT IMMUNOFLUORESCENCE1

Abstract

Human peripheral blood lymphocytes were digested briefly with protease prior to application of indirect immunofluorescence techniques for detecting alloantibodies in sera of patients with chronic renal failure on maintenance hemodialysis. Background staining of intrinsic surface IgM [immunoglobulin M] and cytophilic IgG bound to Fc receptors was eliminated or greatly reduced, enabling detection of B [bone marrow-derived] cell specific antibodies, including cold-reactive types not demonstrable by conventional immunofluorescence or complement-dependent lymphocytotoxicity. The antigenicity of HL-A and other surface membrane determinants was not decreased by protease, although reactivity with certain sera was enhanced. In experiments comparing indirect immunofluorescence using protease-treated cells with complement-dependent lymphocytotoxicity and antibody-dependent, lymphocyte-mediated cytotoxicity assays, indirect immunofluorescence was more sensitive and comprehensive, but not less specific, in defining alloantibodies of a variety of types.