Reactivity of antibodies isolated from uninfected subjects. Three IgG antibodies (Ab1144, Ab929, and Ab931) and one IgM antibody (C14) in threefold dilutions ranging from 50 to 0.2 µg/ml (x axis) were evaluated for reactivity with HIV-1 rgp41 by Luminex assays (A) and for reactivity with a panel of autoantigens by ANA assays (B). The dotted lines indicate the cutoff values ≥120 luminance units used to denote positivity. Binding affinity of Ab1144, Ab929, and Ab931 in dose ranges (starting concentration at 40 µg/ml) to HIV-1 MN gp41 was measure by SPR (C). Data are representative of at least two separate experiments.