Dissociation between increased surface expression of Gp165/95 and homotypic neutrophil aggregation

J. P. Buyon, S. B. Abramson, M. R. Philips, S. G. Slade, G. D. Ross, G. Weissmann, R. J. Winchester

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Whether homotypic neutrophil aggregation depends on the quantitative increase of gp165/95 molecules (Mac 1, CR3) recruited to the cell surface during activation was studied using mAb of the CD11b group that recognize distinct epitopes encoded by the α-subunit of this glycoprotein. After the addition of antibody MN41, neutrophils did not aggregate in response to a chemoattractant, FMLP. Blockade of preexisting surface gp165/95 by mAb MN41, followed by removal of the excess antibody from the mixture, was used to show that the molecules of gp165/95 newly expressed in response to stimulation by a chemoattractant were incapable of effectively mediating the induced cell-cell interactions of aggregation. Flow cytometry studies confirmed that binding of unlabeled antibody MN41 did not block further increases in surface expression of gp165/95 after stimulation with FMLP. These data suggest that molecules of gp165/95 exhibit two functionally distinct forms, one, present on the surface of freshly isolated neutrophils, that becomes competent to mediate the aggregation response upon activation by a stimulus and a second form that can be translocated to the cell surface by the stimulus but is greatly diminished if not lacking in the ability to participate in that aggregation event.

Original languageEnglish
Pages (from-to)3156-3160
Number of pages5
JournalJournal of Immunology
Issue number9
StatePublished - 1988
Externally publishedYes


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