Immunology Unit

C-reactive protein (CRP) is a member of the pentraxin family which opsonises S. pneumoniae through its binding to phosphorylcholine. In addition, CRP binds to Fcy receptors: FcyRI with high affinity and, probably, FcyRIIA with lower affinity. Binding to FcyRIIA was suggested to depend on a polymorphism at residue 131 of the receptor, HH individuals being poorer binders compared to RR. To clarify the role of CRP binding to FcyRHA and functional activities upon interaction, neutrophils from HH and RR individuals were incubated with CRP in the presence or absence of pneumococci type 3. No difference in activation as determined by IL-8 synthesis, respiratory burst and phagocytosis were seen between HH and RR donors. Since CRP increases its serum concentration up to 1000 fold above the normal level, we also compared acute-phase concentrations of CRP with normal levels for neutrophil functions. Normal (: 510 ýtg/ml) and acute-phase (10- 100 4g/ml) levels increased IL-8 production in the presence or absence of pneurnococci. A similar pattern was seen for extracellular reactive oxygen. There was a five-fold increase i