IgA deficiency and circulating immune complexes in Neapolitan children with fatal acute respiratory infections.

Immunoglobulins, C3 and C4 levels and circulating immune complexes have been measured on admission sera from 34 children admitted to a Naples hospital during the winter of 1978/79 with severe, usually fatal, acute respiratory infections and in age-matched controls from Rome. The Naples sera were characterised by low IgA, C3, and C4 levels, increased IgM and IgG concentrations, and high titres of circulating immune complexes. These immunological abnormalities could explain the high concentration of fatal cases.