[Immunoglobulins A, G and M and C3 and C4 components of the complement in pneumonia in infants under 1 year of age].

The findings of 69 autopsies of children of the first year of life who died from pneumonia were examined. The children were found to have a significant lowering of IgA and IgG and an increase of IgM which correlated with the immunomorphological appearance of the organs of immunogenesis. The concentration of components C3 and C4 of complement was reduced. The reduction appeared most remarkable in +viral and bacterial pneumonias. The conclusion is drawn that in children of the first year of life, pneumonias eventuating in lethal outcomes may occur in primary and secondary immunodeficiency states, since the immune mechanisms are also implicated in the pathogenesis of pulmonary tissue lesions.