Dysfunction of the mononuclear phagocytic system in sepsis

An in vivo study has been undertaken of the Fc(IgG) receptor-mediated phagocytic capacity of macrophages (clearance of anti-rhesus D-coated-51 Cr-labelled autologous erythrocytes, expressed as half-lives) in 15 cases of sepsis to establish its behaviour and correlate this function to levels of circulating immune complexes (anti-Clq-nephelometry). Five patients with low activity (2261 +/- 859 minutes) developed septic shock; the other ten showed high activity (5.8 +/- 1.5 minutes) and did not develop septic shock. Differences from the control group (30 +/- 12 minutes) were found (p less than 0.001). Receptor activity was related to the presence of circulating immune complexes (p less than or equal to 0.001; delta = 0.862) but not to age, sex, or the presence/absence of splenomegaly during the illness. Eight patients responded favourably; seven patients died; but the receptor activity was not related to this. During sepsis it is possible to find higher Fc(IgG) receptor-mediated phagocytic capacity of macrophages. Excessive formation of circulating immune complexes has a negative influence on Fc(IgG) receptor-mediated phagocytosis. This activity of macrophages, measured at the start of the sepsis, was not associated with the final outcome of the patients' illness (cure or death).