Phenotypical and functional characteristics of tumor-infiltrating lymphocytes from colon carcinomas stimulated with rIL-2 and rIL-4 in vitro: comparison with lymphocytes of the normal colon mucosa and the peripheral blood.

The phenotypical composition of tumor-infiltrating lymphocytes (TIL) from colorectal carcinomas was compared with that of intraepithelial lymphocytes of the autologous normal colon mucosa (IEL) and autologous peripheral blood lymphocytes (PBL). The CD4+/CD8+ ratios of the freshly isolated TIL, IEL and PBL were comparable and always > 1. CD25+, HLA-DR+ and CD56+ cells accumulated significantly in the TIL, while CD45RA+ cells were less frequent compared to the autologous IEL and PBL. CD29+ memory-cells were found with the highest frequency in the TIL. Stimulation with rIL-2 in vitro induced an outgrowth of CD56+ cells in the TIL. Concordantly the expression of CD3+ and the alpha/beta T-cell receptor was low. In a standard 51Cr-release assay these phenotypically LAK-cells representing effectors displayed an unspecific lytic activity against the autologous tumor as well as against allogeneic K562 and Daudi targets. The number of CD56+ cells could be reduced in TIL and PBL by simultaneous stimulation with rIL-2 and rIL-4, while the number of CD3+ cells increased.