ENHANCED EXPRESSION OF HUMAN MONOCYTE COMPLEMENT (C3B) RECEPTORS BY CHEMOATTRACTANTS

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  • 1 January 1980
    • journal article
    • research article
    • Vol. 39  (3) , 768-775
Abstract
The capacity of various leukoattractants to enhance or unfold receptors from complement (C3b [fragment b of complement component 3]) on human blood monocytes was studied. A number of recognized monocyte chemoattractants including casein, supernatants from [Corynebacterium parvum 10390 [Propionibacterium acnes]] 10390 and from human lymphocytes (cultured in the presence or absence of phytohemagglutinin) and the formyl-methionyl peptides, F-Met-Leu-Phe, F-Met-Met-Phe and F-Met-Phe, increased the percentage of monocytes which formed rosettes with Ig[immunoglobulin]M-sensitized sheep erythrocytes coated with complement. Comparable results were achieved irrespective of whether purified components or whole serum was used as a source of complement. There was no significant increase in EAG [erythrocyte-antibody (Ig coated)] (Fc) rosettes with doses of casein which gave enhancement of C3b receptors. A small degree of complement receptor enhancement was observed with histamine but the unformylated peptides, Met-Leu-Phe and Met-Met-Phe, were without apparent effect. Maximal receptor enhancement was obtained at 30 min but when the leukoattractant was removed, enhancement was reversible, returning to normal values in approximately 120 min. Monocyte complement receptor enhancement increased with temperatures between 0.degree. and 37.degree. C. These data confirm and extend the previous findings on leukoattractant-induced enhancement of complement receptors on human monocytes. The phenomenon may have potential as a clinical test for monocyte function in health and disease.