Studies on H-2 specificities on mouse tumour cells by a new microradioassay.

Seven mouse tumour cell lines of different aetiology and origin were tested for the expression of surface alloantigens using twenty-four well defined H-2 alloantisera and anti-Thy 1.2. We used a new radioassay that involves antibody-complement treatment of the tumour target cells followed by postlabeling the surviving tumour cells with 14C-thymidine. With a relatively high frequency the anti-H-2 sera were reacting differently with the tumour cells than with respective syngeneic lymphoid cells. Thirty-six anomalous reactions out of 129 investigated were detected. Absorbtion experiments performed with H-2 antigen positive or negative lymphoid cells revealed a striking similarity between these extra-specificities and H-2 specificities of foreign haplotypes. The results are discussed in relation to the biological importance of the extra-specificities, both with regard to origin (derepression) and function (transplantation antigen properties).