DIFFERENTIAL EXPRESSION OF TYPE-I INSULIN-LIKE GROWTH-FACTOR RECEPTORS IN DIFFERENT STAGES OF HUMAN T-CELLS

Insulin-like growth factor I (IGF-I) has been implicated to play a regulatory role in T cell development and in T cell function. We investigated the expression of type I IGF receptors on human peripheral T cells related to the maturation and activation stage using the type I IGF receptor-specific monoclonal antibody alpha IR3. It appeared that 87% of the CD4(+)CD45RA(+) cells and 66% of the CD8(+)CD45RA(+) cells were alpha IR3(+), whereas only 37% of the CD4(+)CD45R0(+) cells and 38% of the CD8(+)CD45R0(+) cells bound alpha IR3. We also found that the fraction of alpha IR3(+) cells within in vivo or in vitro activated (HLA-DR(+)) T cells is markedly lower than in nonactivated (HLA DR(-)) cells. In vitro phytohemagglutinin-activated T cells and CD4(+)CD45R0(+) cells activated with recall antigens also contained less alpha IR3(+) cells (1-6%) than nonactivated cells (30-54%).