BRAIN AND THYMUS LIPID INHIBITION OF ANTIBRAIN-ASSOCIATED ϑ-CYTOTOXICITY

Reif and Allen (1-3) demonstrated that 0-antigen was present on the surface of mouse thymocytes and a number of murine leukemia cells, in brain tissue and, to a lesser extent, in lymph nodes and spleen.They later showed that 0-antigen was controlled by a single locus with two alleles: 8-AKR found in AKR mice, and 0-C3H found in most inbred strains of mice, including CBA.Golub (4) has employed the fact that 0-antigen is present in brain to produce an antibrain-associated 0-antiserum (BA0) 1 by injecting mouse brain into rabbits.The activity of BA0 antiserum parallels that of AKR anti-0 C3H and C3H anti-0 AKR.The relationship between O-C3H, 8-AKR, and BA0 has recently been shown by Clagett et al. (5) and Peter et al. (6) to consist of a complex system of shared and unshared antigens between mouse 8-C3H, 0-AKR, and rat Lewis (Le) thymocytes.The immunochemical reactions of lipids have been the subject of a review (7).Among the most studied of these antigens of haptenic determinants are the Forssman hapten (8, 9), cytolipin R, K, and H (7), and the A B H and Le b isoantigens (10).Antisera can be prepared toward gangliosides with extended immunization schedules using pure gangliosides or brain (11,12).We now describe the partial characterization of a lipid which has been isolated from mouse thymocytes and brain, and which is capable of inhibiting the cytotoxicity of anti-BAO antiserum.The data presented here are consistent with the proposal that BAO antigen is GDlb ganglioside. Materials and MethodsAnimals.---CBA/J female mice 4-12-wk old were used as donors of thymocytes and brains" Young Dutch Belt rabbits (3 kg) were used for preparation of antisera.Thymocytes.--Care was exercised upon removal of mouse thymus to avoid contamination with surrounding mediastinal lymph nodes.Thymuses were placed in Eagle's minimal essen-