SEQUENTIAL PRECIPITATION OF MOUSE THYMOCYTE EXTRACTS WITH ANTI-LYT-2 AND ANTI-LYT-3 SERA .1. LYT-2.1 AND LYT-3.1 ANTIGENIC DETERMINANTS RESIDE ON SEPARABLE MOLECULAR-SPECIES

Abstract

Anti-Lyt-2.1 and anti-Lyt-3.1 sera were employed for sequential precipitation of NP-40 [Nonidet P-40 detergent] extracts of 125I-labeled C57BL/6-Lyt-2a, Lyt-3a thymocytes (Lyt-2.1, Lyt-3.1) to determine whether these alloantigenic determinants are present on the same or different molecular species. Treatment of extracts with anti-Lyt-3.1 serum and SaCI [formaldehyde-fixed Staphylococcus aureus, Cowan I strain] completely precipitated Lyt-3.1 and Lyt-2.1-specific components, whereas treatment with anti-Lyt-2.1 serum reduced by approximately 37% the quantity of labeled species subsequently precipitable by anti-Lyt-3.1 serum. When 125I-labeled thymocytes were subjected to mild trypsinization before NP-40 extraction, the quantity of radioactive components precipitated by anti-Lyt-2.1 serum was essentially unchanged, but that of anti-Lyt-3.1-precipitable components was greatly reduced. Sequential precipitation of extracts of trypsinized thymocytes with anti-Lyt-2.1 and anti-Lyt-3.1 sera demonstrated that these molecular species were precipitated independently. Lyt-2.1 and Lyt-3.1 antigenic determinants appear to reside on different molecular species. Some Lyt-2.1 and Lyt-3.1-positive molecules appear to be complexed with each other in the NP-40 extract. This association of Lyt-2.1- and Lyt-3.1-positive species was dependent upon components that were labile to trypsinization of intact thymocytes.