Generation of cytotoxic cells from murine bone marrow by human recombinant IL 2.

Murine bone marrow (BM) cells were cultured in recombinant IL 2 (rIL 2) and interferon-alpha, -beta, and -gamma, and cytotoxic activity against YAC cells was determined in a 4-hr 51Cr-release assay. rIL 2 at 20 U/ml was the only lymphokine that consistently induced significant cytotoxic activity within 3 days of culture, peaking around 5 to 7 days. The cytotoxic cells generated are heterogeneous, consisting of at least two populations of cells: a) NK-1+, Qa-5+, AsGm-1+ Thy-1+/-, Lyt-2- cells, similar to natural killer (NK) cells, and b) NK-1-, Qa-5+, AsGm-1+ Thy-1+, Lyt-2+ cells, similar to cytotoxic T lymphocytes. The precursor/accessory cells of these BM cytolytic cells maintained in 20 U/ml of rIL 2 were Qa-2+, Qa-5+, Thy-1+/-, AsGM-1+/-, and NK-1+/- but Lyt-2-. They also lysed NK-resistant targets, P815 and BW5147, and the antigenic phenotypes of these cells were similar to those that lysed YAC cells. These studies indicate that IL 2 alone is adequate to generate cytotoxic activity from BM and that these cytotoxic cells were similar to splenic NK cells.