Anti-HIV-1 antibody avidity is correlated with clinical status in infected children

Avidity of antibodies to gp41 and p24, CD4 cell count, and free and dissociated p24 antigen were assessed in 37 HIV-1-infected children, in order to evaluate whether the avidity of anti-HIV-1 antibodies is related to the disease status in perinatally infected children. The HIV-infected children were divided into two groups. Group 1 included 25 children: 2 not symptomatic (CDC category N), 12 mildly (A) and 11 moderately (B) symptomatic; group 2 included 12 children with severe clinical manifestations (C). The same parameters were assayed longitudinally in four children: two with long-term nonprogressive disease and two with fatal outcome. Antibody avidity was significantly higher in group 1 than in group 2 children (7272 +/- 4788 vs. 2624 +/- 1344 D50, p < 0.01), as was the CD4 cell count (1295 +/- 1122 vs. 348 +/- 488 cells/mm3, p < 0.01). No differences between the two groups were observed in either free or dissociated p24 antigen. Combined measures of antibody avidity and CD4 cell count showed the best correlation with the clinical status (r = 0.57, p = 0.001). In the two children with nonprogressive disease the antibody avidity remained high throughout the follow-up, whereas in those with clinical deterioration its decline preceded, by at least 8 months, the drop in CD4 cells and, by at least 23 months, the appearance of AIDS. In conclusion the avidity of anti-HIV-1 antibodies is reduced in HIV-infected children with advanced disease state and seems an earlier predictor of disease progression than CD4 cell count.