Enhanced destruction of lymphoid cell lines by peripheral blood leukocytes taken from patients with acute infectious mononucleosis.

The cytotoxicity of peripheral blood leukocytes from normal human donors and from patients with EBV-associated infectious nomonucleosis (IM) has been determined for human lymphoid cell lines (LCL) containing Epstein-Barr virus (EBV) DNA. In a 51Cr release assay, mononuclear leukocytes from all donors are spontaneously cytotoxic. Leukocytes taken from patients within the first 2 weeks of overt IM are significantly more cytotoxic. This increased cytotoxicity declines to the spontaneous level as the disease progesses. The increase shows no correlation with the degree of lymphocytosis but a positive correlation with numbers of circulating atypical cells. The reaction is apparently not directed against histocompatability antigens, known EBV membrane antigens, or other characteristics of fresh human lymphoid cells. Susceptibility to damage is shared by bone marrow-derived (B) cell lines but not thymus derived (T) cell lines. EBV-gene products cannot be soley responsible for expression of the unknown characteristic. Transformation of B cells with EBV in vivo or in vitro, however, may trigger its expression