MRNAs ENCODING CCKB BUT NOT CCKA RECEPTORS ARE EXPRESSED IN HUMAN T LYMPHOCYTES AND JURKAT LYMPHOBLASTOID CELLS

Abstract

We previously reported the existence of pharmacologically related gastrin/CCKB type receptors (CCKB-R) in a variant of Jurkat T lymphoblastoid cells (JK(CD3 −CD4 +)). We studied here the expression of mRNAs encoding CCKA and CCKB receptors in various human white cells by means of Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Using CCKB-R specific primers, we detected a significant expression of CCKB-R mRNA in JK(CD3 −CD4 +) cells. These transcripts were also expressed, at a lower level, in two other Jurkat clones (JK(CD3 +CD4 −) and JK(CD3 +CD4 +)), in peripheral blood lymphocytes (PBL) and in purified CD4 + and CD8 + lymphocytes. Activation of Jurkat cells and PBL by T cells mitogenic lectins (jacalin, phytohemaglutinin) did not modify CCKB-R mRNA expression. In all these cells, using CCKA-R specific primers, we could not amplify any specific cDNA fragment corresponding to this receptor. Neither CCKB-R nor CCKA-R mRNAs could be detected in monocytic cells. Our data show for the first time a constitutive expression of CCKB-R transcripts in lymphoid cells. Moreover, the modulation of immunocyte functions by cholecystokinin-related peptides could occur through CCKB-R rather than CCKA-R and affect lymphocytes rather than monocytes.