Studies on the Effect of Specific Antisera on the Metabolism of Cellular Antigens

Abstract

Abstract The metabolism of thymus leukemia (TL) antigens of ASL-1 leukemia cells (TL 1,2,3) as measured by specific activity (cpm/mg protein) of isolated TL antigens was investigated during antigenic modulation. TL antigens prelabeled with 3H-fucose or 125I disappeared more rapidly from ASL-1 cells undergoing modulation than from control nonmodulating cells. Although TL antigens were released into the culture medium the total quantity in the medium of modulating cells was the same as that released from control cells not undergoing modulation. The synthesis of TL antigens in cells undergoing modulation was indistinguishable from control cells. No difference in the incorporation of 3H-fucose into TL antigens was noted in cells incubated with TL antiserum and cells incubated with normal mouse serum. The alteration in the metabolism of membrane-associated antigens after reaction with specific antisera was unique for TL antigens. Antibodies directed against antigens other than TL, also present in the TL 1,3 antiserum used for modulation, failed to induce changes in the metabolism of these non-TL antigens. Furthermore, no significant changes in the degradation of H-2a antigens were noted during modulation of TL antigens. The synthesis of TL antigens by normal thymus and spleen cells was also studied. TL- A/J spleen cells or TL- C57BL/6 thymocytes failed to incorporate 3H-fucose into membrane components which were precipitable by TL 1,3 antiserum, whereas TL + A/J thymocytes were found to synthesize actively TL antigens.