Measurement of salivary, urinary and fecal secretory IgA levels in children with partial or total IgA deficiency.

We measured salivary, urinary and fecal secretory IgA (sIgA) levels in 11 children with total IgA deficiency and in 6 children with partial IgA deficiency using an ELISA technique. This was based on flexible microplates coated with antisecretory component (SC) and peroxidase-conjugated anti-IgA as a second antibody. Selective IgA deficiency is diagnosed as a serum IgA concentration < or = 0.05 g/l; partial IgA deficiency is diagnosed as a serum concentration of IgA > 0.05 g/l but 2 SD below normal levels. No salivary or fecal sIgA, and only low levels of urinary sIgA, were detected in the selective IgA-deficient group. The partial IgA-deficient children presented with low levels of salivary, urinary and fecal sIgA. Fecal sIgA levels correlated with salivary sIgA levels (p < 0.01) but not with urinary sIgA levels (p > 0.05) in the IgA-deficient patients. We found that all the children with partial IgA deficiency, except one, had detectable, but low values of secretory IgA. Our data suggest that these patients also have a partial mucosal IgA deficiency.