SENSITIVE DETECTION AND EARLY PROGNOSTIC-SIGNIFICANCE OF P24 ANTIGEN IN HEAT-DENATURED PLASMA OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE 1-INFECTED INFANTS

Immune complex formation causes underdetection of p24 antigen in human immunodeficiency virus (HIV) infection. Briefly boiling diluted plasm a releases all complexed antigen, which can then be measured by some c ommercial assays. In a retrospective pediatric cohort study, the speci ficity of this procedure in 390 uninfected samples was 96.9% after ini tial testing and 100% after neutralization. Sensitivity among 125 post natal infected samples was, at a detection of 2 pg/mL, 96.0% (97% neut ralizable) compared with 47.7% for regular antigen (76% neutralizable) , 96% for polymerase chain reaction, and 77% for viral culture. The hi gh sensitivity and specificity of heat-denatured antigen was confirmed by prospectively testing 113 additional samples. Quantitative analysi s of samples from infected infants showed low levels of p24 antigen in 29% of cord blood sera, a postnatal increase to levels that were duri ng the first 6 months of life inversely associated with survival, and persistence of antigenemia thereafter independent of clinical status. Prevalence and antigen levels were significantly lower in mothers. The persistent antigenemia in children indicates that their immune system s cannot restrict HIV expression as efficiently as those of adults.