Lack of effect of orally administered human serum immunoglobulin on the normal human oral and intestinal microflora.

The aim of this study was to investigate the influence of large doses of orally administered human IgG on the normal gastrointestinal microflora of healthy volunteers since human immunoglobulin has been tried as oral prophylaxis and therapy in gastrointestinal infections. Ten adult healthy volunteers received 10 g of IgG orally, once daily for three consecutive days. Aerobic and anaerobic microorganisms were identified in the saliva and stool specimens, using morphological, biochemical and serological tests and gas-liquid chromatography. Although the immunoglobulin preparation contains antibodies against a variety of microorganisms, there were no significant changes in the numbers of different aerobic and anaerobic microorganisms due to the oral intake of the immunoglobulin. IgG may, therefore, be used against pathogens without disturbing the normal oral and intestinal microflora.