The substance reacting with SRBC (sheep red blood cells) and rabbit IgG. Isolation under mild conditions from rat thymus.

A factor reacting with SRBC and rabbit IgG was obtained under mild conditions from rat thymus and spleen. The isolation procedure includes incubation of thymocytes or splenocytes with IgG-cellulose adsorbent, destruction of cells, washing the adsorbent and elution of an adsorbed material at pH 2. This preparation as well as the purified substance previously obtained by affinity chromatography on IgG-cellulose columns were found to agglutinate both SRBC and autologous erythrocytes. Preincubation in 1% SDS leads to dissociation of the preparation into several components separated by gel electrophoresis. A probable relation of this structure to the rosette forming capacity of T-lymphocytes is discussed.