Enrichment of rat NK cytotoxicity for H2-negative murine embryonal carcinoma cells by panning and short-term culture in TCGF

The rat natural killer (NK) cell, defined here by spontaneous lysis of H2-negative embryonal carcinoma (EC) cells, was investigated with respect to its antigenic phenotype. Rat spleen cells were separated by panning into adherent and non-adherent populations after incubation with monoclonal antibodies defining differentiation antigens of rat lymphoid cells. This method achieved considerable NK enrichment in some of the panned populations (for example, W3/13 non-adherent cells, up to 20-fold), but emphasized the heterogeneous surface antigen expression of the NK cell type. These enrichment procedures were used to establish bulk cultures of rat NK cells which increased in specific activity over several weeks when grown in T cell-growth factor (TCGF) and could be cloned in soft agarose.