Preparation of antigenically active membranes from solid murine lymphomas and fibrosarcomas

Plasma membrane preparations were obtained from solid lymphosarcomas and fibrosarcomas by disrupting the tissues with a mechanical press. The subcellular fractions were isolated by differential centrifugations and examined by electron microscopy. The membrane-enriched fractions were also assayed for protein content and analyzed in SDS-polyacrylamide gel electrophoresis; a fairly good reproducibiltiy was found comparing different membrane preparations derived from the same tumor. The H-2 antigenic activity of the different membrane preparations was demonstrated in vitro by the inhibition of the C'-dependent 51Cr-release assay using monospecific H-2 alloantisera. The specificity of the assay was ascertained by the lack of inhibition of unrelated monospecific H-2 alloantisera and by a dose-response relationship between the amount of added membranes and the observed inhibition. The immunogenicity of the membranes was assessed in vivo by immunizing allogeneic mice that developed anti-H-2 alloantibodies. The possible mechanisms of the tissue disruption by the press are also discussed.