EXPRESSION OF MEMBRANE-ASSOCIATED C-REACTIVE PROTEIN BY HUMAN MONOCYTES - INDICATIONS FOR A SELECTIN-LIKE ACTIVITY PARTICIPATING IN ADHESION

We have shown previously that rat liver macrophages (Kupffer cells) ex press a membrane-bound form of C-reactive protein (mCRP) on their surf ace which is identical to a galactose-specific particle receptor activ ity. We now establish the presence of mCRP on human monocyte-macrophag es using immunocytochemistry with an anti-neoCRP specific monocloncal antibody and RNA-RNA in situ hybridization to demonstrate the presence of CRP-specific mRNA. Concomitant with mCRP expression, cells exhibit galactose-dependent uptake of particles coated with lactosylated bovi ne serum albumin. Adhesion experiments on fibronectin-coated surfaces that mCRP on human blood monocytes may act as a selectin-like adhesion molecule, mediating initial carbohydrate-specific contacts which are followed by peptide-specific recognition via integrin receptors.