RESUMO
This study evaluated differences in the expression of three surface antigens (H-2Kb, H-2Db, and Thy 1.2) of two EL4 T-lymphoblastoid cell lines. The two cell lines, EL4 (G-) which is not virus infected and the MuLV-producing subline EL4G +, had the same cytographic size distribution and a doubling time of twenty-four hours. Reflective of the morphological similarities, the expression of the T-cell specific alloantigen Thy 1.2 for the two lines did not differ. In contrast to the Thy 1.2 expression, antibody-detectable H-2Kb and H-2Db activity was much greater on the MuLV-producing EL4G + subline as indicated by fewer cells needed to remove 50% of the cytotoxic activity of the antibody ( AD50 ). Comparison of the EL4(G-) AD50 / EL4G +AD50 ratio indicated an increase in H-2b antigen expression on EL4G + of 15.6 fold for H-2Kb and 7.81 fold for H-2Db. To investigate the possibility of a selective association between MuLV and EL4G + H-2 antigens, the specific activity for H-2Kb, H-2Db and Thy 1.2 of EL4G + membrane and MuLV preparations obtained from EL4G + cultures was compared. The relative proportion of (Thy 1: H-2Kb: H-2Db) in membrane preparation was (1.14:2.45:1.95) compared to the proportion (0.31:3.15:0.95) in virus preparations. Although the amount of Thy-1 activity was markedly elevated in the virus preparation, H-2b antigenic activities were not significantly different in the two preparations. These data are consistent with an active association of lymphoid surface glycoproteins and MuLV, and suggest an association between productive MuLV infection and an increase in the expression of H-2 antigens in the EL4G + cell cultures.