Expression of the high responder/non-responder human FcyRIL Analysis by PCR and transfection into FcR COS cells.

Autor: Tate, Bruce J., Witort, Ewa, McKenzie, Ian F. C., Hogarth, P. M.
Předmět:
Zdroj: Immunology & Cell Biology; Apr1992, Vol. 70 Issue 2, p79-87, 9p
Abstrakt: Distinct differences in the capacity of monocyte FcyRII of different individuals to bind or not bind mouse IgG1 defines a polymorphism of FcyRIIa and has previously been defined as the high responder (HR) or low responder (LR) polymorphism of FcyRII. The precise definition of the molecular basis of the human HR/LR polymorphism of FcyRIIa from the peripheral blood mononuclear cells of normal individuals has been determined by anti-CD3 induction of T cell proliferation, the polymerase chain reaction (PCR), nucleotide sequencing, transfection and IgG binding. Amplification of first strand cDNA from mRNA isolated from mononuclear cells was performed by PCR using primers specific for the sequences encoding the leader and cytoplasmic sequences of FcyRIIa, which is normally expressed in monocytes. Sequencing of the PCR products and transfection of these to FcyR cells indicated that in FcyRIIa of HR or LR individuals; (i) three nucleotide substitutions (CA to TG and G to A) resulted in the change of glutamine to tryptophan at position 27 (first extracellular domain) and arginine to histidine at position 131 (second extracellular domain); (ii) expression of cDNA encoding the various combinations of these indicated that arginine at position 131 was essential for IgG1 binding whereas the amino acid changes at position 27 had no effect; and (iii) IgG1 at high concentration bound to all allomorphic forms of FcyRIIa. These results indicate that position 131 in the second extracellular domain of FcyRIIa is intimately involved in immunoglobulin binding. Furthermore, the apparent inability of IgG1 to bind to FcyRIIa of non-responder individuals is not absolute in that immune complexes sensitized with a high concentration of MlgG1 will bind to non-responder-type FcyRIIa. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
Externí odkaz: