Structure and Biological Functions of Human IgD

Abstract

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 IgD 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.

Genetic Control of Immune Responsiveness in Man

“…The role of an X-linked gene in immunoglobulin (Ig) production is well demonstrated in man by the sex-linkage of congenital Bruton-type agammaglobulinaemia, which is transmitted by females but expressed only in males [6]. Females as compared with males have higher levels of serum immunoglobulin, including IgM and IgG [8] and also IgD [23] but not IgA [S] or IgE [17], higher levels of natural antibody to various antigens [38], and give higher responses on immunogenic challenge, shown in man after challenge with monomeric flagellin [39] and tetanus toxoid [ 121. Moreover, this X-linked gene effect on humoral immune responses may account in part for the higher risk for females of developing autoantibodies, as shown in population studies [19], and of developing autoimmune disease [26].…”

Measles virus-specific IgD antibodies in patients with subacute sclerosing panencephalitis.

“…This report led to the suggestion that IgD may function as a lymphocyte receptor for B-cell differentiation (3). The receptor role for IgD, however, does not account for IgD found in the serum (4) nor its apparent antibody activity (5). Investigations with serum IgD have been hampered because of normally low levels of IgD in the serum and the degradation of IgD molecules by plasmin activity (6).…”