CHANGES IN SERUM IgE AND IgM LEVELS IN HETEROPHIL-ANTIBODY POSITIVE INFECTIOUS MONONUCLEOSIS (MA+IM)

141 serial blood samples were obtained from 19 patients (14-40 yr) with HA+IM including 9 from whom pre-illness samples were available. All specimens were simultaneously studied immunologically, and most were studied hematologically and serologically. IgE was determined by a paper disc solid phase radioimmunoassay, and IgM by single radial immunodiffusion.IgE showed an average rise to a peak 276% of the pre-illness level (PIL), usually within the 1st 10 days and always by the 17th day. This was followed by a drop to 41% of PIL, with a gradual return to PIL after about a year.IgM showed a similar trend but the relative changes were less pronounced. On the average, the peak was 176% of PIL and the nadir 75%, of PIL. The IgE peak preceded the IgM peak in 14% and coincided with it in 56% of the cases.A 2 to 5 fold rise in serum IgE is a relatively constant paniment of HA+IM which usually coincides with the peak of atypical lymphocytes and often precedes other responses.