Cold lymphocytotoxic antibodies in nasopharyngeal carcinoma.

Sera from patients with nasopharyngeal carcinoma (NPC), a disease associated with Epstein-Barr virus (EBV), were found to be cytotoxic at 15% degrees C in the presence of complement for a panel of human lymphocytes, with a higher frequency than those of matched controls. The cold lymphocytotoxic antibodies (LTA) responsible for this activity have the same properties as those described in sera from individuals with acute viral infections. The frequency and geometric mean titres (GMT) of LTA varied with the origin of the patient (Chinese larger than North African larger than Caucasian) and the stage of the disease (Stage IV larger than Stage I). A positive correlation between LTA and anti-EBV titres was found with regard to antibodies to the viral capsid antigen (VCA) and the EBV-specified nuclear antigen (EBNA). The absence of correlation between LTA and anti-early antigen (EA) titres probable reflects the complex relationships existing between viral infection and LTA production, but is compatible with the hypothesis that LTA acts as an immune regulatory mechanism in viral infections.