Surface membrane changes in lymphocytes from patients with infectious mononucleosis.

Peripheral blood lymphocytes from 20 patients with acute infectious mononucleeosis (IM) were studied for cell aggregation and for cap formation by concanavalin A (Con A). The lymphocytes from these patients showed 5.2+/-1.5% cells with a Con-A-induced cap and a high degree of cell aggregation without Con A, compared to 27.7+/-3.2% caps and a low degree of cell aggregation with normal lymphocytes. The lymphocytes from IM patients were fractionated to enrich for T and B cells. There was a low frequency of cap formation in both T and B cells, but the high degree of celll aggregation without Con A only occurred with B cells. Studies with four patients in clinical remission from acute IM have shown that the frequency of Con-A-induced cap formation only returned to normal more than 3 months after the beginning of clinical remission and that even at 6 months the cells still showed a high degree of cell aggregation. The results indicate that a high degree of B-cell aggregation and a low percentage of B and T cells with a Con-A-induced cap were associated with acute IM and that the changes associated with a high degree of B-cell aggregation were by themselves not sufficient to cause the disease.