Transient neutrophil aggregation in a patient with infectious mononucleosis.

Transient neutrophil aggregation is reported in a case of infectious mononucleosis. The phenomenon was observed on a blood film patient just before splenic infarction and decreased after splenectomy. The aggregation was so important that differential blood count could not be done. A high serum level of circulating immune complexes was found, and fluorescent spots inside of granulocytes, presumably engulfed immune complexes, could be observed. It is suggested that C activation associated with high immune complexes in infectious mononucleosis is a possible pathogenetic mechanism inducing PMNs aggregation and immune tissue damage.