Infectious mononucleosis: increase of high-affinity E-receptor-bearing lymphocytes.

The increase of T lymphocytes in infectious mononucleosis (IM) is shown to be due to an increase of 'active' (early erythrocyte rosette-forming) T cells: 67.2 +/- 18.3% of IM lymphocytes were 'active' versus 34.7 +/- 14.9% of control lymphocytes. IM was also associated with an increase of lymphocytes demonstrating E receptors at 20 degrees C (E20-R). This phenomenon was not related to the heterophile antibody titre and could not be demonstrated with ox or rabbit erythrocytes. Patients with other lymphoproliferative diseases did not show an increase of E20-R-positive cells or of 'active' erythrocyte rosette-forming cells (E-RFC). Re-rosetting experiments indicated that E20-R and 'active' E-RFC belong to overlapping populations of cells. A double-gradient separation technique was shown to be superior to the conventional Ficoll-Isopaque method for the demonstration of 'active' and total T cells. A high proportion of T lymphocytes were also recovered in the granulocyte layer by this technique, indicating a selective loss of these cells by the conventional technique.