STRUCTURE AND BIOLOGIC FUNCTIONS OF HUMAN IGD .11. IDENTIFICATION AND ONTOGENY OF A RAT LYMPHOCYTE IMMUNOGLOBULIN HAVING ANTIGENIC CROSS-REACTIVITY WITH HUMAN IGD

Abstract

Chicken anti-human Ig[immunoglobulin]D antiserum (anti-.delta.) has demonstrated and antigenically cross-reactive homologue on rat lymphocytes. IgD and IgM are the only cell surface Ig detectable by the lactoperoxidase radiolabeling technique employed. Although rat surface IgD is antigenically distinct from rat IgM, the respective H chains apparently co-electrophorese in 10% polyacrylamide-SDS [sodium dodecyl sulfate] gels. Rat .delta.-chain has an aparent M.W. of 73,000 daltons and exhibits a minor 65,000 dalton component which probably represents a partially degraded .delta.-chain. The ontogenic emergence of rat IgD occurs approximately 3.5 wk after birth, whereas IgM is apparent by 6 days of age. As in the human, IgM developes before IgD. IgD receptors are undetectable in the thymus but are present in increasing levels in spleen, blood, lymph nodes and Peyer''s patches.