Guinea pig immune response related histocompatibility antigens. Partial characterization and distribution

It has previously been demonstrated that guinea pig alloantisera directed at strain 2 and strain 13 membrane antigens block specific lymphocyte activation in immune response gene controlled systems. In this communication the authors describe the partial characterization of the antigens against which these antisera are directed (the 2 and 13 antigens) and, in addition, that of the B antigen which by distribution resembles the human HL A and mouse H 2 major histocompatibility antigens. Lymphoid cells from strain 2 and strain 13 guinea pigs were surface labeled with ¹²⁵I by the lactoperoxidase technique. Nonidet P 40 extracts of these labeled cells were precipitated by sandwiches of strain 2 antistrain 13, strain 13 antistrain 2, or outbred anti B antisera, followed by rabbit anti guinea pig immunoglobulin antisera. Precipitates were dissolved in sodium dodecyl sulfate (SDS) and electrophoresed on SDS polyacrylamide gels. Radioactive peaks representing the 2 and B cell membrane antigens were obtained from strain 2 lymph node cells, as well as from a B lymphoid cell population (L₂C leukemia cells) and a T lymphocyte population (strain 2 peritoneal exudate lymphocytes [PELs]). Radioactive peaks representing the 13 and B cell membrane antigens were obtained from strain 13 lymph node cells and strain 13 PELs. All anti B precipitates produced two peaks when electrophoresed on SDS polyacrylamide gels; one representing an antigen with a mol wt of approximately 45,000, and one representing an antigen with a mol wt of about 12,000. Both may be components of a single protein. All anti 2 and anti 13 precipitates produced a single peak when electrophoresed on SDS polyacrylamide gels. By means of this technique, both the 2 and 13 antigens were found to have a mol wt of approximately 25,000. By molecular weight criteria, as well as by previously investigated distributional criteria, the B antigen is similar to the human LA and Four antigens, and to the mouse D and K antigens, and the 2 and 13 antigens are similar to the mouse Ia antigens.