[Secretory immunoglobulin A in the blood sera of healthy and ill persons]

Sera of healthy and sick persons were tested for the presence of secretory IgA (SIgA) and free secretory component (SC) SIgA was present in the blood of healthy persons in low concentrations (1.07 mg/100 mg), and free SC was absent. Infectious and somatic diseases, in which damage of the epithelial covering of the gastrointestinal and respriatory tracts was possible, were accompanied by increased blood SIgA content. There was also noted a distinct relationship between the blood SIgA concentration and the severity of infectious diseases and pneumonia supervention. In these cases the SIgA level proved to rise.