Analysis of antigenic heterogeneity within individual 3-methylcholanthrene-induced mouse sarcomas.

A method of establishing sublines by trocar transplantation in vivo was used to analyze possible cellular heterogeneity with regard to tumor-specific antigens in individual methylcholanthrene-induced sarcomas. Differences in antigenic specificity were found in at least 1 of the 9 pairs of sublines obtained, respectively, from opposite poles of 9 different primary tumors. No evidence suggested such differences among 7 pairs of sublines similarly derived from later transplant generations. The lack of variation in antigenic specificity between members of subline pairs obtained from later transplant generation tumors suggested that antigenic specificity was a stable characteristic. Even when derived from later transplant generations, the sublines of a particular tumor sometimes differed in growth potential, and/or immunizing capacity, and/or responsiveness to immunity. There was little or no correlation between variations in the two parameters: immunizing capacity and responsiveness to immunity. These findings led to the interpretation that immunizing capacity and responsiveness to immunity behaved like partially independent variables, and that variations in these parameters probably depended on factors other than, or in addition to, cellular antigen content per se. The marked, random, spacial heterogeneity revealed within the tumors in cellular growth rate and antigenic properties suggests that changes seen during serial tumor transplantation are probably due to random clonal variation and subsequent selection.