Presence of serum IgD and IgD-containing plasma cells in the mouse

A new technique which makes use of anti-δ-specific allo- or heteroantisera coupled to Sepharose 4B has been employed to investigate the presence of IgD molecules in the sera of three mouse strains. The sera were reacted with the insoluble immunosorbents, and the eluted material was labeled with ¹²⁵I prior to antigenic or sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. This material reacted with anti-δ or anti-L chain reagents, but not with other anti-class-specific antisera and, after reduction, was resolved in three discrete bands in SDS-PAGE. The fastest of these bands comigrated with L chain, whereas the other two moved identically to mouse lymphocyte surface δ chains. Immunofluorescence studies on fixed smears of spleen and Peyer's patches' cells revealed the presence of a small but consistent number of IgD-containing plasma cells.