Characterization of serum neutralization response to the human immunodeficiency virus (HIV)

To determine the clinical significance of human neutralizing antibodies to the human immunodeficiency virus (HIV), we measured serum neutralization in patients with different clinical outcomes following HIV infection. Serum neutralization titers ranged from less than 1:5 to 1:100. The neutralization response after HIV infection appeared slow, with neutralization titers remaining low, at or below 1:5, at 7 months following seroconversion. Comparison of 78 HIV seropositive subjects with AIDS, AIDS-related complex, or no symptoms failed to reveal any significant differences in titer which correlated with clinical status. However, a greater proportion of AIDS patients with Kaposi's sarcoma (11/12) had neutralization titers of 1:20 or greater than did AIDS patients with opportunistic infections (2/11). Serum samples were analyzed by Western blot for their reactivity to specific viral proteins. Clinical status could not be predicted by a particular serological profile. However, sera which reacted with the HIV major envelope glycoprotein gp120 tended to have higher neutralization titers, suggesting that gp120 may be a target of anti-HIV neutralizing antibody in man.