Deficiency of IgM.

Abstract

An 8½-month-old infant with absent IgM had recurrent Pseudomonas infections. IgG and IgA, but no IgM-containing plasma cells, were identified in the spleen by immunofluorescence. The spleen and lymph nodes lacked germinal centers, but Peyer9s patches and the appendix were normal. The absence of IgM was perhaps genetically determined because the father9s serum IgM was also low. This may have predisposed to the Pseudomonas infection, since antibodies to Pseudomonas are predominantly IgM.