Structure and biological functions of human IgD. IV. Ontogeny of human serum immunoglobulin D(IgD) as related to IgG, IgA and IgM.

The ontogeny of serum IgG, IgA, IgM and IgD in 312 members of a southern United States population was studied. Circulating IgD was found in all adolescents and in 97% of the adults tested. IgD levels increased until adult life. Females had statistically significantly higher levels of Igtd than did the males of their respective age groups. The children investigated showed an accelerated development of adult levels of all immunoglobulins, particularly IgG, IgM and IgD. These departures from previously reported norms emphasize the importance of regional variability and demonstrate the necessity for characterizing local patterns of humoral immunologic development. Our total lack of knowledge concerning the biological function of IgD could be corrected if more laboratories would measure IgD as part of their routine immunoglobulin screening programs.