Tumoricidal effect of interleukin-2-activated killer cells in canines

We investigated the effect of both partially purified (TCGF) and recombinant interleukin-2 (rIL-2) on the tumor-directed cytotoxic activity of canine peripheral blood mononuclear cells (PBMC) using three normal canines. No cytotoxic activity was displayed by unstimulated effector cells at 3 h of incubation; however, the cytotoxic effect was observed in a 16-h assay. PBMC of all canines displayed significant levels of lytic activity after stimulation for 4 to 7 days with both types of IL-2 against a variety of allogeneic and xenogeneic neoplastic cells in 3-h 51Cr release assay. The cytotoxic activity of cultured cells increased proportionally in the 16-h assays. Morphological examination of the May-Grünwald and Giemsa stained cytocentrifuged slides of cultured cells on each day of assay showed an increase in large granular lymphocytes (LGLs) beginning on day 4 and reaching a peak on day 7 of culture.