[Specific IgA in the serological diagnosis of viral infections]

In acute viral infections, specific IgM antibodies appear early and persist for a short period of time; by contrast IgG antibodies persist longer. The diagnostic significance of specific serum IgA is still discussed. We observed that in acute systemic infections, serum IgA appear early and are mainly polymeric (p-IgA) whereas monomers (m-IgA) appear in late convalescence. On the other hand, in secondary infections or in reinfections these immunoglobulins are mainly represented by monomers. In mucosa confined infections, serum IgA are almost absent suggesting that their synthesis is not related to mucosal stimulation.