IMMUNOLOGY

Detailed explanation-1: -(16) recently described two subsets of IgD+ B cells in human tonsils and PB, respectively, that can be distinguished by the expression of the CD27 cell surface antigen, a member of the TNF receptor family. This antigen is expressed on essentially all IgD−, i.e., class-switched and IgM-only, PB B cells.

Detailed explanation-2: -In contrast to the other immunoglobulin isotypes, the IgD class is mainly expressed on the surface of B lymphocytes; in the serum of rodents and primates it is found only in very low levels.

Detailed explanation-3: -IgD (IgD) is a monomeric antibody isotype that is expressed in the plasma membranes of immature B-lymphocytes. IgD is also produced in a secreted form that is found in small amounts in blood serum.