Evaluation of basic procedures for adoptive immunotherapy for gastric cancer

Peripheral blood lymphocytes (PBL) of gastric cancer patients in advanced stages showed lymphokine activated killer (LAK) activities comparable to those of healthy donors, suggesting potential applicability of LAK cells induced from PBL stimulated with recombinant interleukin-2 (rIL-2) in adoptive immunotherapy (AIT) for gastric cancer. In order to generate a large number of LAK cells from PBL, lymphocytes were cultured with both rIL-2 and phytohemagglutinin (PHA). In this culture, the numbers of cells increased to a greater extent than those in culture with rIL-2 alone but cytotoxic activity did not augment, thus suggesting that this procedure would not afford sufficient clinical effects. On the other hand, a large number of LAK cells with high anti-tumor activities were efficiently induced from spleen cells of the patients by culture of rIL-2; hence clinical usefulness of these LAK cells is anticipated. In regional lymph node lymphocytes (RLNL) cultured with rIL-2, the cytotoxic activities were lower than in those induced in PBL, and a characteristic increase of CD8 + CD11 + suppressor T cells was observed after incubation with rIL-2. Nevertheless, an increase of CD4 + 4B4 + helper inducer T cells was also observed in RLNL after the culture with rIL-2. Furthermore, high cytotoxic activities were induced in RLNL in some cases in which metastasis to the regional lymph nodes was not detected. When gastric cancer patients were pretreated with biological response modifiers (BRM), especially with Lentinan, LAK cells from PBL showed higher NK and LAK activities as compared with those of patients without BRM pretreatment.