Need for Caution in Interpretation of Western Blot Tests for HIV

To the Editor.—  With widespread use of screening programs for antibodies against the human immunodeficiency virus (HIV) in blood banks since July 1985, the number of cases of reported false seropositivity is increasing. Modifications in the screening strategies should be strongly considered to avoid the psychological trauma suffered by falsely seropositive blood donors. We report a case that further underlines the urgent need for controlled diagnostic tests.

Report of a Case.——  A 55-year-old asymptomatic woman was advised by the Montreal Red Cross that she was seropositive for HIV, as determined by an enzyme-linked immunosorbent assay (ELISA) and confirmed by a Western blot test.¹ The most probable source of contamination was her husband, who had received 3 units of blood while undergoing surgery in our hospital two years previously. The husband's serum was sent to our laboratory, but no antibodies against HIV were detected by either ELISA or indirect immunofluorescence.