Raised Serum Levels of IgE in Infectious Mononucleosis

The concentration of immunoglobulin (Ig) E was determined by a radioimmunosorbent technique in sera of 24 patients with infectious mononucleosis. Four patients had extremely high levels in sera obtained 7–10 days after the onset of the disease. These levels were as high as those hitherto seen only in patients with allergic diseases or worm infestations. The high concentrations decreased rapidly. The remaining patients had normal, likewise decreasing, or subnormal levels. A similar trend for IgM was observed, confirming previous results. IgG, IgA and IgD were elevated in a few patients. The immunoglobulin changes noted may be interpreted as a sign of the intense immune response characteristic of infectious mononucleosis.