Immunoglobulin Changes in the Course of Infectious Mononucleosis

The levels of γG, γA and γM have been determined by the Oudin tube method in 26 male and 19 female patients during the course of I.M. A control group consisting of 32 male and 27 female healthy young adults were also analysed. All classes of immunoglobulins were elevated already during the earliest stage of clinically manifest infectious mononucleosis (I.M.), indicating a long incubation period. The highest levels of γG were observed from 10 to 30 days after onset of fever (average 170 per cent of the normal mean), and a slow return towards normal levels took place. Peak levels for γA (163 per cent) occurred simultaneously, but a somewhat more rapid return to normal levels was evident. Increased levels of γM were a constant feature of acute I.M. and the highest levels (300 per cent) were observed from 1 to 20 days after onset of the illness. During convalescence a rapid return towards normal levels was observed, which seemed to parallel the disappearance of Downey cells. Whereas no sex difference was present among the I.M.‐patients γM‐levels were higher in the female controls.