THE SELF-REACTIVE ANTIBODY REPERTOIRE OF NORMAL HUMAN SERUM IGM IS ACQUIRED IN EARLY-CHILDHOOD AND REMAINS CONSERVED THROUGHOUT LIFE

The authors have used a quantitative immunoblotting technique to analy se the antibody repertoire of IgM in cord blood and in the serum of yo ung children, young adult males and aged males directed towards antige ns in homologous tissues utilized as sources of self antigens. The rea ctivities of IgM with self antigens exhibited striking homogeneity and invariance among newborns. Self-reactive IgM repertoires of children, young adults and aged males were markedly conserved among individuals and comprised most of the anti-self reactivities that prevailed in ne onates. Reactivities of IgM with bacterial antigens showed a high degr ee of homogeneity among newborns but were more diverse in children, yo ung adults and elderly individuals. Diversity of IgM reactivities with self and non-self antigens did not vary significantly with aging. Pri ncipal component analysis (PCA) and linear discriminant analysis (LDA) of the data discriminated between self-reactive IgM repertoires of ne wborns and children, but failed to discriminate between repertoires of children, young adults and aged males. The data indicate that the sel f-reactive antibody repertoire of IgM differentiates during the first years of life and remains relatively constant thereafter.