Tumor infiltrating lymphocytes in malignant brain tumors.

When treated with CD3 moAB (aCD3) (1 microgram/ml) and human natural IL-2 (nIL-2) 1000 U/ml, during the exponential phase of growing: 200 U/ml tumor infiltrating lymphocytes (TIL's) from brain tumors could be expanded. Due to the low percentage of lymphocytes in malignant brain tumor tissue (1%) it was not possible to separate the tumor bearing lymphocytes from the tumor cells by a Ficoll Hypaque gradient separation. This resulted in a co-culture of both lymphocytes and tumor cells in which a serum free medium was used. To generate TIL's at all, it was necessary to supplement this culture medium with 20% of the supernatant of cultures of lymphokine--activated killer cells. In 9 out of 12 cases we obtained total growth factors in the range between 10(4) and 10(14) (average 3.6 x 10(7)). These growth were reached after 6 to 13 weeks including up to 3 weeks of an initial lag period during which no cell growth was observed. We noted a decrease in CD8+ cells, whereby the predominant cell type at the end of the cultures was CD3+ and CD4+. The levels of their cytotoxic activities against K-562 and Raji cells were low in contrast to those of CD3 and nIL-2 stimulated cells which were obtained from carcinomas.