Virus-specific polymeric immunoglobulin A antibodies in serum from patients with rubella, measles, varicella, and herpes zoster virus infections.

More than 85% of the immunoglobulin A (IgA) antibodies in normal adult serum are monomeric (m-IgA). By contrast, virus-specific IgA is mainly polymeric (p-IgA) in sera from patients with rubella, measles, and varicella. Specific m-IgA antibodies only reach quantitative significance in late convalescence. In patients with herpes zoster, on the other hand, a varying response was observed: in three of six sera, specific IgA was absent or at a very low titer, whereas in the remaining three cases, a high titer of both p-IgA and m-IgA was noted. These results suggest that in the initial response to rubella, measles, and varicella-zoster viruses, specific IgA first appears as p-IgA and only later becomes, or is replaced by, m-IgA.