Comparative Studies on Polymer‐Type Serum and Exocrine IgA

Abstract

Polymer‐type IgA from serum, reflected in high molecular weight A‐myeloma globulins were studied in the ultracentrifuge, by starch gel electrophoresis and by antigenic analysis. Size heterogeneity was confirmed. No antigenic differences were found between the monomer and the polymer of serum IgA. Peptic digestion of 10 S IgA revealed that the polymerising tendency residues in the Fc‐fragment of the molecule. No antigenic structures, specific for exocrine IgA (colostrum, saliva) could be demonstrated in polymer‐type IgA of serum origin.

Human Secretory Immunoglobulins

“…Previous attempts to disclose shared antigenic determinants of secretory and serumtype polymer IgA, have been unsuccessful (Ballieux et al 1968). The same authors also were unable to find antigenic differences between monomers and polymers of serum IgA.…”

“…In this connection it is of interest that 0.1 M j3ME and alkylation (Vaerman et al 1965), but not 0.1 M cysteine or 6 M urea (Ballieux et al 1968), can produce depolymerization of serum polymer IgA. Its 7s…”

“…IgA units are hence disulfide-bridged through chemical groups apparently located on the Fc portion of the &-chains (Ballieux et al 1968). These groups probably are involved in the P determinant shared by secretory and serum-type polymer IgA; and one may thus assume that their 7 s IgA subunits primarily are linked in a similar way.…”