THE COMPLEMENT-BINDING AND ABSORPTIVE CAPACITY OF HUMAN WHITE BLOOD CELLS TREATED WITH NEURAMINIDASE1

Human lymphocytes treated with Vibrio cholerae neuraminidase (VCN) are more susceptible to cytotoxic human alloantisera than are sham treated cells. Sera from most normal or immunized donors showing no detectable anti-HL-A activity gave strong positive reactions with almost all VCN-treated isologous or autologous lymphocytes. Less than 10% of the sera tested were unreactive against all VCN-treated cells. Family studies utilizing VCN-treated lymphocytes have revealed patterns of antigens that segregate independently from HL-A. The absorptive capacity of both VCN-treated and sham treated leukocytes for cytotoxic human alloantiserum is dependent on the class (reaction strength) of the ceEs used. Although VCN treatment does not affect the hierarchy of cell classes, which is based on HL-A reactions, VCN-treated cells absorb more antibody activity than sham treated cells. Absorption of a serum sample with sham treated leukocytes removed HL-A-related activity as detected by a panel of sham treated cells, but left antibody activity against VCN-treated cells. All detectable cytotoxic reactivity of sera against normal or VCN-treated lymphocytes was lost upon substitution of C6-defi-cient or cobra venom-treated rabbit serum for the routinely used complement source.