Detection of IgA antibody to EBV membrane antigen using Staphylococcus aureus preabsorbed sera is closely associated with nasopharyngeal carcinoma.

The presence of IgA antibody to membrane antigen (MA) of Epstein-Barr virus (EBV) was tested in sera from 48 nasopharyngeal carcinoma (NPC) patients, 40 patients with tumors other than NPC and 46 normal individuals. The sera were preabsorbed with Staphylococcus aureus (SPA) (strain no. 1800) prior to their use in the indirect immunofluorescence test. One hundred percent of the NPC patients had the IgA/MA antibody with a GMT of 1:141. In patients with tumors other than NPC or normal individuals, IgA/MA antibodies were not detectable. The IgA/MA antibodies have been demonstrated in 6 NPC patients lacking detectable antibody levels in the indirect immunofluorescence test using nonabsorbed sera. Our data indicate that preabsorbtion of sera with SPA renders the diagnostic test significantly more sensitive for the detection of the nasopharyngeal carcinoma and can be used for trials on the prognosis of patients.