PMID: 9531311Apr 8, 1998Paper

Dominant-negative effect of the lymphocyte function-associated antigen-1 beta (CD18) cytoplasmic domain on leukocyte adhesion to ICAM-1 and fibronectin

The Journal of Immunology : Official Journal of the American Association of Immunologists
J A Rey-LadinoF Takei

Abstract

The cytoplasmic domains of LFA-1 (CD11a/CD18) are thought to play an important role in the regulation of LFA-1 function. To further elucidate the role of the LFA-1 cytoplasmic domains, we transfected chimeric proteins consisting of the extracellular domain of CD4 fused with the transmembrane and cytoplasmic domains of LFA-1 into T and B cell lines, EL-4 and A20, respectively, and examined their effects on LFA-1-mediated cell adhesion. The CD4/18, but not CD4/11a, chimera profoundly inhibited LFA-1-mediated cell adhesion to ICAM-1, as well as cell spreading following cell adhesion. Unexpectedly, cell adhesion to fibronectin was also inhibited by the CD4/18 chimera. The CD4/18 chimera did not affect the expression of endogenous LFA-1 or the association of CD11a and CD18. Truncation of the carboxyl-terminal 13 amino acid residues of the CD18 cytoplasmic domain of the chimera completely abrogated the inhibitory effect on LFA-1. Among these amino acid residues, the carboxyl-terminal six residues were dispensable for the inhibitory effect in EL-4 cells, whereas it significantly reduced the inhibitory activity of CD4/18 in A20 cells. A larger truncation of the CD18 cytoplasmic domain was needed to fully abrogate the inhibitory effects...Continue Reading

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