Time course of changes in phenotypes of cultured tumor-infiltrating lymphocytes isolated from human colorectal cancer.

A study was conducted to investigate the time course of changes in phenotypes of cultured tumor-infiltrating lymphocytes (TIL) isolated from 5 patients with colorectal cancer. Following initial incubation with protein phytohemagglutinin (PHA-P, final concentration 0.1 w/v%), one of the inducers of interleukin-2 (IL-2) receptor, and recombinant interleukin-2 (rIL-2, 1000U/ml) for 3 days, TIL was further cultured with rIL-2 alone for another 46 to 79 days. Phenotypes of cultured TIL were analyzed by a two color flow-cytometry. The following results were obtained: 1) Yields of TIL isolated from cancerous tissues were 1.0 x 10(6) to 1.6 x 10(6) cells/g wet weight, and TIL grew 31 to 3700 folds in the entire period of culture. These growth rates were significantly higher than those obtained by the conventional method of culture with rIL-2 alone (1 to 720 folds). 2) The population of cytotoxic T cells (CD8(+), CD11(-)) reached the maximum (92%, median value) at 5 weeks of culture, and thereafter gradually decreased to 61% at 9 and 10 weeks. In contrast, the population of activated natural killer cells (CD16(+) and Leu7 (+) or (-)) remained below 4% for the entire period of culture. 3) Maximum enhancement of specific cytotoxic activities of cultured TIL was observed during 3 to 4 weeks in culture, using K562 cells as well as Daudi cells as target cells. In conclusion, addition of PHA-P seems to beneficially affect the growth rate of TIL in culture.(ABSTRACT TRUNCATED AT 250 WORDS)