Comparative study with in situ hybridization and immunocytochemistry in detection of HIV-1 in formalin-fixed paraffin-embedded cell cultures.

The sensitivities of three immunohistological techniques were compared in this study for detecting human immunodeficiency virus (HIV-1) in infected cultured human lymphocytes that had been formalin-fixed and paraffin-embedded. The techniques included in situ hybridization (ISH) with HIV-1 cDNA; immunocytochemistry with HIV-1 p24 monoclonal antibody (ICC-m); and immunocytochemistry with HIV-1 polyclonal antibody from a patient with acquired immunodeficiency syndrome (AIDS) (ICC-p). Procedures were optimized for enzyme digestion and for antibody reaction conditions. HIV-1--infected cells and noninfected control cells were tested. Noninfected controls were uniformally negative by all three methods. Infected cells had the highest positivity rate by the ISH method (p less than or equal to 0.0001), and the ICC-p method was more positive than the ICC-m (p less than or equal to 0.0001). Both the ICC-p and the ICC-m techniques were more positive with the cocultivated cell cultures than the ISH, which was more sensitive with the infected continuous cell line (P less than or equal to 0.0001). The ICC-p method had a lower standard deviation on positive results than either the ICC-m or ISH method. The variability observed with these test procedures, reagents, and specimens suggests that these are important technological parameters in detecting p24, with implications for detecting other HIV-1 markers in infected tissues.