INCREASED EXPRESSION OF FC-GAMMA RECEPTORS ON NEUTROPHILS AND MONOCYTES MAY REFLECT ONGOING BACTERIAL-INFECTION

The Fc gamma R receptors for IgG, Fc gamma RI, Fc gamma RII and Fc gam ma RIII were measured on neutrophils and monocytes from 36 patients su spected of systemic infection. These results were compared with 30 blo od donor controls to assess the level of expression as an early indica tor of bacterial infection. Fc gamma RI expression on neutrophils was found to be significantly increased from patients with systemic or loc alised infections, when compared to the non-infected patient group, i. e., patients with no cultural evidence of bacterial infections, (p = 0 .02, p = 0.04) or normal controls (p < 0.0001, p = 0.0005), Fc gamma R I expression on monocytes was also significantly increased in both of the infected groups compared to normal controls (p < 0.0001, p = 0.001 ); however, no significant difference could be seen when compared with the non-infected patients. Fc gamma RIII was found to be significantl y increased on a subset of monocytes in patients with systemic or loca lised infections compared to the non-infected group (p = 0.009, p = 0. 006) and compared to the normal controls (p = 0.009, p = 0.003). Infec tions caused by gramnegative bacilli induced a higher Fc gamma R respo nse than infection with either streptococci or staphylococci. These da ta suggest that the measurement of Fc gamma RI on neutrophils and Fc g amma RIII on monocytes may be a useful rapid indicator of bacterial in fection.