<i>In Vitro</i> Inhibition of Plaque and Rosette Formation by α Globulin

Abstract

Abstract Recent studies on the α globulin fraction from plasma of normal individuals have shown that it possesses immunosuppressive properties and interferes with lymphocyte functions in vitro. Cooperband et al. (1, 2) have shown that human α globulin inhibits lymphocyte transformation in vitro following phytohemagglutinin (PHA) and specific antigenic stimulation. Since α globulin fraction can also suppress antibody production against sheep red blood cells (SRBC) in vivo (3–6), experiments were conducted to assess its biologic activity in an in vitro system by the hemolytic plaque assay and the rosette formation technique. Materials and Methods. Alpha globulin was isolated from normal human plasma by DEAE cellulose chromatography according to the procedure described by Mannick and Schmid (7). Immunoelectrophoresis and acrylamide gel electrophoresis showed this material to be primarily α2 globulin. Male local adult white rats of a strain developed at the Hebrew University were used in the hemolytic plaque formation and the rosette formation experiments. The animals were injected intraperitoneally with a 2.5 × 108/0.5 ml suspension of sterile washed SRBC in saline. The same amount of antigen was given again 10 days later. The animals were bled 6 days after each immunization.