Low secretory IgA concentrations in oral secretions during the acute phase of infectious mononucleosis.

Although the Epstein-Barr virus (EBV) relation to infectious mononucleosis (IM) has been well established, the question why IM is not compulsory during a primary EBV infection has yet to be solved. Assuming a possible oropharyngeal secretory immunoincompetence as an etiological component of IM, the secretory IgA concentrations in oral secretions during the acute phase of IM was investigated. Low concentrations of secretory IgA in IM patients (n = 18) were found, mean value 0.180 g/l as compared to those in healthy controls (n = 10), mean value 0.680 g/l. Furthermore, diminishing concentrations of secretory IgA were found during the acute phase of IM. There was no corresponding serum IgA decrease. The investigation also revealed that tinidazole, claimed to be beneficial in the treatment of anginous IM, did not affect the concentrations of spit secretory IgA.