Repression of interleukin-2 mRNA translation in primary human breast carcinoma tumor-infiltrating lymphocytes

Human breast carcinoma tumor-infiltrating lymphocytes (TIL) express activat ion antigens in situ indicative of ongoing immune response-CD28, CD45RO, CD 69, CD71, and DR. However, interleukin 2 (IL-2) receptor was poorly express ed: CD25 was detected in only 1/24 samples and CD122 in only 2/24 samples. Furthermore, isolated breast cancer TIL were defective in proliferative res ponse but recover when treated with recombinant IL-2, Nineteen of 24 tumor samples expressed B7-1, B7-2, and CD28 protein, showing that absence of cos timulator proteins or counter ligand was not the basis for TIL proliferativ e deficit. Expression of IL-2 activity was not detected; however, mRNA enco ding IL-2 was produced and translatable in vitro, These findings show that human breast cancer tumor-induced repression of IL-2 RNA translation is the basis of failure of TIL to express the IL-2 receptor and subsequent T cell hyporesponsiveness, (C) 1998 Academic Press.