Surface phenotype of T cells producing growth of mucosal mast cells in normal rat bone marrow culture.

We have previously shown that lymphocytes from Nippostrongylus brasiliensis infected rats, when stimulated with antigen or concanavalin A (Con A) release factors which are comparable with murine IL-3. On addition of these factors to rat bone marrow cultures, mast cells with the morphological and biochemical properties of mucosal mast cells (MMC) proliferate and mature. Here, we use this system, along with monoclonal antibodies against rat T cells and the fluorescence-activated cell sorter (FACS), to isolate the subset of T cells responsible for the production of this MMC growth factor. Lymphocytes from N. brasiliensis infected rats were separated on the FACs into populations with and without the antigens defined by OX19, W3/25 and OX8 monoclonal antibodies; these antibodies label all T cells, T-helper cells and T-cytotoxic/suppressor cells, respectively. The resultant subsets were cultured in vitro with Con A. The supernatants were tested for the ability to induce MMC growth and differentiation in liquid cultures of normal rat bone marrow. The phenotype of the T cells producing this factor was established as being OX19+, W3/25+ and OX8-.