Isoantigenic Specificity of Rabbit Anti-mouse Lymphocyte Sera: Properties in vitro and in vivo of their F(ab′)2 Fragments

Abstract

ANTISERA from rabbits immunized with mouse tissues contain antibodies which detect mouse isoantigenic differences, in addition to the anti-species antibodies¹. I and my colleagues have shown that the Fab′ and F(ab′)2 fragments of mouse isoantibodies block the effect of whole antibody in vitro, and enhance the C57Bl leukaemia E.L.4 in vivo^2,3. Similar results have been obtained with rabbit isoantibodies⁴. It is therefore possible that the F(ab′)2 fragments of rabbit anti-mouse antibodies could have blocking activity on mouse isoantisera, and, furthermore, they may be able to induce enhancement of tumour growth in mice. I describe here the effects in vitro and in vivo of F(ab′)2 fragments of specific rabbit anti-mouse lymphocyte sera.