Studies on the Macroglobulins of Human Serum

THE occurrence of high-titer heterophil sheep-cell agglutinins in infectious mononucleosis is well established; furthermore, all available evidence indicates that these antibodies are exclusively 19S in nature.1 2 3 Recently Calvo et al.4 described 19S cold agglutinins with anti-i specificity in patients with infectious mononucleosis. The primary purpose of this study was to relate quantitative changes in the immunoglobulins, particularly immunoglobulin Class M (IgM),5 to measurable serologic reactions such as heterophil or anti-i antibody activity. In this regard absorption experiments revealed that no more than 1 to 5 per cent of the quantitative IgM increment present in patients with infectious mononucleosis could be . . .