CLINICAL AND IMMUNOLOGICAL CORRELATES OF IMMUNE-COMPLEX-DISSOCIATED HIV-1 P24 ANTIGEN IN HIV-1-INFECTED CHILDREN

It has been reported that HIV-1 p24 antigen (p24 Ag) detection is impr oved after dissociation of immune complexes using acid treatment (ICD assay). In order to evaluate the clinical significance of p24 Ag detec ted by the standard assay and by the ICD assay in pediatric patients, we related these measurements to clinical status, level of p24 antibod y, and percentage of CD4(+) lymphocytes. Fifty-nine plasma specimens f rom 20 symptomatic HIV-1-infected children, collected prospectively ov er a 1-year period, were tested for these markers. Plasma was collecte d at the beginning of zidovudine therapy and similar to 7 and 12 month s thereafter. Compared with the standard assay, the ICD assay showed a higher number of samples positive for p24 Ag (78% versus 34%) and an increase in the levels of p24 Ag (median value of 129 versus 24 pg/ml) . The anti-p24 antibody level was inversely correlated with the p24 Ag level measured by either assay. Four children negative for p24 Ag by both assays had a stable clinical course. In contrast, 50% of the chil dren negative by the standard assay but positive for ICD p24 Ag and 75 % of the children positive by both assays had progression of disease. No patients were positive by the standard assay but negative by the IC D assay. Children whose plasma tested positive by both assays had lowe r percentages of lymphocytes that were CD4(+) by comparison with child ren who were negative by both assays; children whose plasma tested pos itive only by the ICD assay formed an intermediate group. Antigen leve ls decreased in most of the p24 Ag-positive children during zidovudine therapy; however, those children whose levels increased or remained c onstant during therapy were more likely to suffer clinical deteriorati on. Our results suggest that the ICD assay may be useful as an indicat or of disease progression but that better prognostic information is ob tained by considering the results of both assays.