Further studies on the biological properties of guinea-pig IgG1 antibodies: anti-lymphocyte antibodies.

Anti-rat lymphocyte serum was raised in guinea-pigs in order to study the ability of two 7S immunoglobulin classes to prolong the survival of rat skin homografts. Both classes, complement-fixing IgG2 and anaphylactic IgG1, are active, although the threshold for IgG2 activity is higher. This threshold can be lowered when a mixture of both classes is used. Thus, in this system, complement activation is not a requisite, and different mechanisms must come into play according to the class of anti-lymphocyte antibodies used. Moreover, these results have bearings on the postulated regulatory function of IgG1—antigen complexes.