EXPRESSION OF MULTIPLE ATP RECEPTOR SUBTYPES DURING THE DIFFERENTIATION AND INFLAMMATORY ACTIVATION OF MYELOID LEUKOCYTES

ATP can activate both G-protein-coupled signaling systems or ATP-gated channels by stimulating either P2Y-family or P2X-family receptors. Ou r studies indicate that different P2Y- and P2X-family receptors are ex pressed in mature human phagocytic leukocytes and in myeloid progenito r cells. The P2Y(1) receptor is functionally expressed only in early m yeloid progenitor cells, whereas the P-2U/P2Y(2) receptor is expressed in late-stage progenitor cells and in mature monocytes and neutrophil s. The P2X(1) receptor is not expressed in early myeloid progenitors, but it is abundantly expressed when these cells commit to monocytic di fferentiation. However, the expression of P2X(1) and P-2U/P2Y(2) recep tors is significantly down-regulated when myeloid leukocytes are activ ated with proinflammatory cytokines. In contrast, these same inflammat ory stimuli induce a large up-regulation of P(2)Z/P2X(7) receptor expr ession. We propose that the differential expression of ATP receptor su btypes in various myeloid leukocyte populations indicates that these c ells utilize locally released ATP and particular ATP receptors for dis tinct types of autocrine and paracrine communication. (C) 1997 Wiley-L iss, Inc.