Monoclonal antibodies to murine cell surface antigens I. Lyt-1.1

The production and properties of a monoclonal anti-Lyt-1.1 antibody are described. The monoclonal antibody is of the IgG2a subclass, is cytotoxic, and reacts with Staphylococcal protein A. The tissue culture supernatant has the same activity (titer on thymus > 1/1000) as an anti-Lyt-1.1 produced by a standard immunization procedure, and after in vivo passage of the hybridoma cell line, the serum titer was > 1:10 ⁶. The monoclonal antibody has the same strain and tissue distribution as the conventional antibody, including reactions of Lyt-1 congenic strains, and it precipitates a cell surface molecule of m.w. ~ 67,000. In nonprimed mice, there were similar numbers of Thy-1 ⁺ and Lyt-1 ⁺ cells in spleen, lymph node, and thymus. By using the monoclonal reagent, T-helper and T-killer cells in an allogeneic system were shown to be Lyt-1.1 ⁺.