Immunoglobulin A production in ataxia telangiectasia.

Serum from five patients with ataxia telangiectasia contained no detectable immunoglobulin A (IgA). However, there was evidence (by immunofluorescence) of IgA in the bone marrow of the three patients so examined, suggesting that the defect in IgA production was not complete. IgA was in the saliva of all five patients and in the parotid gland of the one patient studied. This is further evidence of IgAsynthesis by the salivary glands.