Virus-specific IgA in serum, saliva, and tears of children with measles.

Measles-specific IgA antibody titres were determined by radioimmunoassay (RIA) for serial serum, saliva and tear samples obtained from 21 children with measles infection, from onset of rash until up to 14 months later. Serum IgA titres rose rapidly after onset of illness and remained detectable throughout the follow-up period. Virus-specific salivary IgA titres peaked at 4 to 7 days after onset of rash and decreased thereafter. Measles-specific lacrimal fluid IgA antibodies remained elevated for long periods of time; however, secretory component-bearing measles-specific antibodies in tears became for the most part undetectable by 1 month after onset of rash. These data raise anew the question of whether some form of viral latency is associated with the presence of virus-specific IgA antibody, or whether such antibody is simply a reflection of immune memory.