ACTIVATION-INDUCED EXPRESSION OF MICA ON T LYMPHOCYTES INVOLVES ENGAGEMENT OF CD3 AND CD28

LUCIANA MOLINERO; MERCEDES FUERTES; GABRIEL RABINOVICH; LEONARDO FAINBOIM; NORBERTO ZWIRNER

JOURNAL OF LEUKOCYTE BIOLOGY

Society of Leukocyte Biology

Lugar: Bethesda, MD (USA); Año: 2002 vol. 71 p. 791 - 797

0741-5400

MICA is an HLA-related cell stress-regulated antigen recognized by cytotoxic cells expressing the NKG2D molecule. Although resting lymphocytes do not express MICA, it can be induced on PHA-activated T cells. Here, we demonstrate by Western blot that MICA is induced on allogeneic-activated CD4(+) and CD8(+) T lymphocytes. Blocking activation with anti-HLA class I, anti-HLA-DR, or anti-CD86 mAb affected the expression of MICA slightly. When T cells were stimulated with anti-CD3 or anti-CD28 mAb plus PMA, a sustained up-regulation of MICA was observed by Western blot, RT-PCR, and flow cytometry. The expression of MICA reached a plateau at day 4 after CD3 engagement and at day 3 after anti-CD28/PMA stimulation. Conversely, the proliferative response reached a peak at day 4. Hence, CD3 or CD28 engagement induces MICA expression on T lymphocytes. This activation-induced expression might participate in NKG2D-mediated cytotoxicity toward activated T cells to maintain homeostasis during an ongoing immune response.