Lymphocytes binding basic protein of myelin; cytophilic serum antibody and effect of adjuvant.

Splenic lymphocytes from guinea-pigs injected with the basic protein of myelin (BPM) in Freund's complete adjuvant (FCA) were shown by autoradiography to contain a significantly (<0.01) greater proportion of lymphocytes binding I-BPM than splenic lymphocytes from control guinea-pigs injected only with FCA; these in turn contained more than splenic lymphocytes from normal guinea-pigs. Splenic lymphocytes from guinea-pigs injected with a synthetic eleven amino acid peptide (containing the main encephalitogenic determinant, for guinea-pigs, of BPM) in FCA did not contain more lymphocytes binding I-BPM than control suspensions from guinea-pigs injected only with FCA. Binding ability was confered on splenic lymphocytes of normal guinea-pigs, and especially on splenic lymphocytes of guinea-pigs injected with FCA, when the cells were held with guinea-pig antisera to BPM, the binding capacity of which was present in the IgG subclass. In contrast, splenic lymphocytes from Lewis rats after injection of BPM of rat lacked the ability to bind I-BPM of rat, as did splenic lymphocytes from normal rats held with potent rat antiserum to BPM of rat. Our results show, for the guinea-pig, that antibody attaches to the lymphocyte surface as antigen receptor, and, for this species at least, may be an important cause of the presence of antigen-binding cells after injection of antigen.