The serologic behaviour of neuraminidase-treated lymphoid cells. Alloantigenicity and complement sensitivity.

Vibrio cholerae neuraminidase (VCN) renders mouse lymphoid cells highly susceptible to the cytolytic effects of alloantibody and complement (C). This increased susceptibility to lysis is not due to unmasking of alloantigens since no increase in alloantibody-binding capacity of VCN-treated cells could be detected. However, VCN-treated cells can be lysed by normal rabbit serum, human serum, and guinea-pig serum even if specific antibody is not added to the incubation mixture. VCN, therefore, while not unmasking strong H-2 histocompatibility antigens, may be capable of unmasking other antigens with which heterologous sera can react. The increased susceptibility to immune cytolysis of VCN-treated cells appears to be related, at least partially, to its extreme susceptibility to C. Complement inactivation by heat totally abrogated the lytic effect, as did C inactivation by ammonium hydroxide, viscarin, and zymosan. In addition, activation of the autologous serum C within the fluid phase by cobra venom factor produced cytolysis only in VCN-treated cells. Thus, VCN renders nucleated cells highly susceptible to lysis by C.