Generation and characterization of a monoclonal antibody that recognizes an activation antigen expressed by a majority of adherent lymphokine-activated killer cells

In an attempt to generate murine natural killer (NK) cell-specific monoclon al antibodies (MAbs) by immunizing Balb/c mice with C57BL/6 (B6) A-LAKs, we have isolated a hybridoma, CS/NicT.2, which secretes an IgM that recognize s a majority of B6 and B6 Rag-1(-/-) A-LAKs. The CS/NicT.2 antigen is highl y expressed by A-LAKs, but only at extremely low levels on resting splenocy tes, suggesting that its expression is tightly associated with IL-2 activat ion, Among the cell lines examined, only CTLL-2 expresses the CS/NicT.2 ant igen at relatively high levels. A low level of CS/NicT.2 staining is also d etected on resting allo-specific cytotoxic T lymphocytes (CTL) clones, AB.1 and C11. In addition, a similar low level of CS/NicT.2 staining is detecte d on the T-helper cell line HT-2, The CS/NicT.2 antigen is upregulated by i onomycin but not by phorbol 12-myristate 13-acetate (PMA). For the CTL clon es examined, CS/NicT.2 staining is also dramatically increased by anti-TCRb eta or anti-CD3(epsilon) stimulation, Protease treatments of CTLL-2 show th at this antigen is proteinase K sensitive, but relatively resistant to tryp sin digestion. Furthermore, the CS/NicT.2 antigen exhibits a relatively fas t turnover rate as assessed by proteinase K and cycloheximide treatments of CTLL-2, suggesting that the CS/NicT.2 antigen may have a short half-life o n the cell surface.