[Culture of TCGF-dependent immunosuppressor T cells in gastric cancer patients and phenotypic characterization of the cell surface, using monoclonal antibodies and a fluorescence-activated cell sorter (FACS)].

We cultured immunosuppressor T cells from gastric cancer patients using T-cell growth factor (TCGF) prepared from human tonsil or spleen. Peripheral blood lymphocytes cultured for 3-4 weeks with TCGF strongly inhibited the lymphocyte-proliferative response to alloantigen or PHA. Quantitative fluorescence measurement for immunological analysis of phenotypic characterization of the cells was made on a FACS-IV, using monoclonal antibodies (anti Leu-I, anti Leu-2a, anti Leu-3a, anti Leu-4, anti Leu-5, anti Leu-7, anti HLA-DR) and goat anti-human immunoglobulin. Immunosuppressor T cells grown in the presence of TCGF showed phenotype Leu-1+, 2a+, 3a-, 4+, 5+, 7-, HLA-DR+, human Ig-. Culture of immunosuppressor T cells activated by tumor cell antigen in vitro was successful only when the cells derived from patients with disseminated, nonresectable type of gastric carcinoma. Our findings suggest that TCGF-dependent immunosuppressor T cells are the result of a large tumor burden; this may explain the depression of in vitro or in vivo cell-mediated immune responses frequently found in such cancer patients.