A Study of Antibodies Produced by Spleen Fragments in vitro . ∗

Abstract

Summary and conclusion

Cultures of spleen fragments from rabbits which had been immunized by subcutaneous injection of H.S.A. in complete Freund' adjuvant were shown to be capable of continuing antibody synthesis and producing a secondary response on exposure to antigen in vitro. Gel nitration studies of humoral and in vitro antibody on Sephadex G-200 columns showed that they were of similar molecular weight. Additional purification on CM Sephadex columns indicated that serum antibody could be further separated into 2 fractions having antibody activity. The in vitro antibody also separated into 2 fractions at the same ionic strength of eluting buffer, but in the case of 2 media [one from cultures having a secondary response initiated in vivo (R₃) and one inititiated in vitro (R₄3)] a third active peak was partially separated by eluting with 0.2 M buffer and striking enhancement of antibody was achieved. The cause of this enhancement has not as yet been identified, but these studies suggest that a distinct population of antibody molecules is produced in the secondary response in vitro, which can be detected only after CM Sephadex filtration.