Molecular basis for a polymorphism involving Fc receptor II on human monocytes
Clark, M.R.; Clarkson, S.B.; Ory, P.A.; Stollman, N.; Goldstein, I.M.
Journal of Immunology 143(5): 1731-1734
1989
ISSN/ISBN: 0022-1767 PMID: 2527271 Document Number: 346550
IgG Fc receptor II (Fc.gamma.RII) on human monocytes is polymorphic with respect to its appearance on gels after isoelectric focusing and with respect to its ability to mediate T lymphocyte proliferation induced by murine anti-CD3 mAb of the IgG1 isotype (i.e., its ability to bind murine IgG1). To determine the molecular basis for this polymorphism, we isolated total cellular RNA from PBMC of responders and nonresponders (defined by Leu-4-induced [3H] thymidine incorporation) and synthesized corresponding cDNA. Sequences encoding the extracellular domain of Fc.gamma.RII were then amplified using the Taq polymerase chain reaction. Amplified DNA fragments were cloned into pUC vectors, and sequenced. Analysis of clones from two on responders revealed a single base change (G for A) at position 519, which would result in the substitution of a histidine for an arginine at residue 133 in the mature Fc.gamma.RII protein. These findings suggest that the polymorphism involving human monocyte Fc.gamma.RII results from allelic variation of a single gene.