Alien H-2 Antigens on a Chemically Induced Fibrosarcoma: Further Evidence in Crude Membrane and Soluble Extracts of the Tumor

Abstract

Crude membranes (CM) were obtained from in vivo subcutaneous nodules of the methylcholanthrene-incuded BALB/c fibrosarcoma C-1 by forcing tumor fragments through a mechanical press and subsequent differential centrifugation. This immunogenic tumor has been previously shown to express both H-2^d and extra H-2^k-like antigens. Original H-2^d and alien H-2^k antigenic activities were present in CM C-1 as judged by the specific inhibition of the C'-dependent cytotoxicity of monospecific H-2 alloantisera on normal ⁵¹Cr-labelled lymphoid cells. Both K- and D-end private H-2^d antigens (31 and 4), and H-2^d public antigens 8, 29, 35 were detected in CM C-1. In addition, the alien H-2K^k.23 private specificity and the public H-2^k.1, 5, and 25 were also found in CM C-1. A weak but reproducible activity attributable to the D^k private antigen 32 was also revealed in this material. A hierarchy in the expression of both H-2^d and H-2^k specificities was evident in CM C-1 which paralleled, although with an overall lower antigenic activity, those of two other BALB/c (H-2^d) fibrosarcomas and of a C3Hf (H-2^k) lymphoma, respectively. CM from normal BALB/c and C3Hf spleens, while expressing higher amounts of all the tested H-2 antigens, displayed a hierarchy of the different specificities similar to that of neoplastic tissues. Crude soluble (CS) material was obtained from CM C-1 by deoxycholate treatment and was tested in the inhibition assay for the presence of H-2^d and alien H-2^k antigens. Only specificities with the highest expression in CM were found in CS, i.e. H-2.4 and 29 for H-2^d and H-2.25 for H-2*. Both CM and CS from C-1, but not from another control BALB/c sarcoma, were able to significantly inhibit the activity of an oligospecific serum to the K^k-coded antigens.