Infectious Mononucleosis: the Prognostic Significance of Various Changes of the Blood Leukocytes

Peripheral blood smears were studied in 25 selected cases of infectious mononucleosis. In 7 the onset was acute and the course severe, in 6 the onset was acute and the course mild, in 6 the onset was gradual and the course severe, and in 6 the onset was gradual and the course mild. The predominance of any of the various types of lymphocytes of infectious mononucleosis was not noted to bear any relationship to the clinical course, although type III lymphocytes and granulocytic immaturity may be more frequently seen when the onset is acute. When toxic changes are present in the granulocytes, the clinical course is likely to be severe.