The expression and biological activity of IL-2 receptor on a human pancreas cancer cell line

Macrophage-induced neutrophil apoptosis

Macrophages (Mphi) contribute to the resolution of early inflammation by recognizing and ingesting apoptotic polymorphonuclear neutrophils (PMN). In addition, experiments reported here demonstrated that Mphi can actively induce PMN apoptosis. Coculture of cells from 2- or 5-day-old wounds in rats, or of Mphi purified from such preparations, with PMN-rich wound cell populations obtained 1 day after wounding increased PMN apoptosis by >3-fold. Neither resident- nor Proprionibacterium acnes-elicited peritoneal Mphi-induced PMN apoptosis. Apoptosis was not mediated by a soluble factor and required E:T contact. Fixed wound-Mphi and membrane isolates from viable Mphi were as effective as intact cells in inducing PMN apoptosis. Mphi-induced apoptosis was inhibited by peptide Arg-Gly-Asp-Ser, anti-beta3 (CD61) Ab, CD36 peptide, or anti-TNF-alpha Ab. Soluble TNF-alpha did not induce PMN apoptosis. In additional studies, K562 cells (negative for beta3, TNF-alpha, and Fas ligand) transfected to express either alphavbeta3 integrin, an uncleavable membrane form of TNF-alpha, or both were used in cocultures with wound PMN. Only the double transfectants were able to induce PMN apoptosis, an effect inhibited by anti-beta3 (CD61) or anti-TNF-alpha Abs. These results demonstrate that wound Mphi induce PMN apoptosis through a constitutive effector mechanism requiring both intercellular binding through integrin-ligand interactions and membrane-bound TNF-alpha.

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

Human breast carcinoma tumor-infiltrating lymphocytes (TIL) express activation antigens in situ indicative of ongoing immune response-CD28, CD45RO, CD69, CD71, and DR. However, interleukin 2 (IL-2) receptor was poorly expressed: CD25 was detected in only 1/24 samples and CD122 in only 2/24 samples. Furthermore, isolated breast cancer TIL were defective in proliferative response 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 costimulator proteins or counter ligand was not the basis for TIL proliferative deficit. Expression of IL-2 activity was not detected; however, mRNA encoding 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.