Monoclonal anti thy 1.2 antibodies from hybridoma HO13-4 do not react with mouse natural killer cells.

The susceptibility of NK cells and immune cytotoxic T-cells to treatment with (a) monoclonal anti thy 1.2 antibodies from hybridoma HO13-4, (b) rabbit anti-mouse T-cell antiserum and (c) gamma globulins prepared from AKR/J anti C3H/HeJ antiserum was studied in the presence of rabbit complement. Monoclonal anti thy 1.2 antibody treatment completely abolished the cytotoxic activity of immune T-cells derived from C57BL/6J mice (H-2b) immunized with (C57BL/6J x DBA/2)F1 spleen cells (H-2bd) against P815 (H-2d) target cells. The same treatment had no significant effect on the NK activity of spleen cells from unimmunized mice against YAC target cells. Rabbit anti-mouse T-cell and mouse anti theta antisera also abrogated completely the immune T cell activity of spleen cells. This treatment however also resulted in a partial loss of NK activity. These results indicate that conventional anti theta antisera contain antibodies which recognize antigenic specificities on T-cells as well as on a population of NK cells. The cross reactivity is not a result of thy 1.2 antigen expression on NK cells and T-cells as recognized by the monoclonal antibodies. The specificity recognized by the monoclonal antibody (HO13-4) is only expressed on T-cells.