FIGURE 4.

The anti‐αGal antibody comprises significant parts of human anti‐pneumococcal antibody reactivities. Inhibition of IgG reactivity with different serotypes of pneumococci by the presence of different disaccharides. Reactivity was quantified by flow cytometry. (A) Normal human IgG (nhIgG) was used as source of anti‐pneumococcal IgG. The reactivity with each of ten serotypes was challenged by Galα3Gal at 37 mM. Circles show the results of separate experiments, and the bars are the geometric mean for reactivity with each serotype (note that geometric means are not defined for datasets including negative values). Results are marked by an asterisk when the 95% confidence interval of the mean does not contain 0 (and therefore is considered significantly different from 0). The inhibited antibodies reacted with the soluble Galα3Gal and are therefore anti‐αGal. Thus, the level of lost reactivity represents the percentage of anti‐αGal that comprised the anti‐pneumococcal reactivity of nhIgG. (B) As in the previous panel, except that the reactions were challenged by Glcα2Fru. Glcα2Fru did not inhibit the reactivity of nhIgG with any serotype. (C) As in panel A, except that the antibody source was plasma samples from different healthy persons tested against serotype 7F pneumococci. (D) As in the previous panel, except serotype 9V pneumococci were used as target pneumococci