Agreement study between two laboratories of immunofluorescence as a confirmatory test for human immunodeficiency virus type 1 antibody screening

Abstract

A total of 114 serum specimens from 76 blood donors, 21 patients with acquired immune deficiency syndrome or acquired immune deficiency syndrome-related complex, 7 multiply transfused patients, 3 hemophiliacs, and 7 others were tested for anti-human immunodeficiency virus type 1 (HIV-1) antibody by enzyme immunoassay (EIA) and Western blot (WB) and then blindly tested by immunofluorescence (IF), independently, in two separate laboratories. The IF technique used acetone-fixed HIV-1-infected E cells and uninfected HUT-78 cells mixed at a 1:3 ratio in one spot on a glass slide and uninfected HUT-78 cells (to assess nonspecific fluorescence) alone in a second spot. Of 114 serum specimens, 85 were repeat EIA positive, and 21 of these were WB positive. A total of 129 of 134 of the IF results (included were 20 duplicates) were identical between laboratories, for a Kappa agreement statistic of 0.93. All five IF results discordant between laboratories were EIA repeat positive and WB negative. Included in the study were eight WB-indeterminate sera, of which five blood donor serum specimens and one hemophiliac serum specimen were IF negative and two acquired immune deficiency syndrome serum specimens were IF positive. As a confirmatory test for HIV-1 antibodies, IF provided a faster alternative or supplementary test for confirming EIA results.

Immunofluorescence assay in India for confirmation of HIV-1 infection using a T-cell line infected with defective HIV-1

“…It has been reported that if the IF assay is performed in a diagnostic laboratory with experience in IF, the false-positive rate should be less than 1% on initial testing and should approach zero on repeat testing. 14 In the present study no false positivity was observed.…”

“…The IF assay has been used successfully in diagnostic laboratories for three decades and has proven to be an acceptable test for the detection of anti-HIV-1 antibodies. [14][15][16][17][18][19][20] We have described here the performance of one such IF assay using L-2 cells as an alternative antigen source, within the context of a state reference [ ( F i g u r e _ 2 ) T D $ F I G ] laboratory that is accustomed to screening large numbers of suspected cases of HIV infection.…”