Familial chronic mononucleosis.

A syndrome of chronic mononucleosis occurred in two members of a family. Symptoms were chronic malaise and fatigue; recurrent upper respiratory tract infections; and mild, variable immune abnormalities. Intermittently positive heterophil titers were present for more than 2 years after acute infectious mononucleosis. Epstein-Barr-virus-specific antibodies were persistently abnormal. In the proband, the R component of the early antigen complex was present for 3 years and she never developed normal antibodies to Epstein-Barr nuclear antigen. Her brother had low to absent Epstein-Barr nuclear antigen titers, and antibodies to both the R and D component of the early antigen complex. Primary and acquired immunodeficiency states can show abnormal Epstein-Barr-virus-specific serologic findings that may reflect an attempt by the host to limit virus spread in the presence of deficient immune responses. This action may result in alterations of the Epstein-Barr virus-latent state, and lead to a chronic active infection and a syndrome of chronic mononucleosis.