The role of surface IgD in the response to thymic-independent antigens.

Abstract

An alloanti-.delta. antibody was prepared by immunizing C57BL/Ka mice with BALB/c spleen cells. Its specificity for .delta.-chain was demonstrated by immunoprecipitation and SDS-PAGE [sodium dodecyl sulfate-polyacrylamide gel electrophoresis] of 125I-labeled membrane proteins from BC8 spleen cells. BC8 mice possess C57BL/Ka background genes and BALB/c IgH genes. The anti-.delta. reagent without complement inhibited the primary in vitro anti-TNP [trinitrophenyl] antibody response to TNP-AECM[aminoethyl carbamylmethyl]-Ficoll by BC8 spleen cells, although it had no effect on the anti-TNP response of congenic C57BL/Ka spleen cells, which lack the .delta.-allotype identified by this antibody. The anti-.delta. antibody had no effect on the anti-TNP response of BC8 spleen cells to TNP-BA [Brucella abortus], except at limiting antigen concentrations. TNP-AECM-Ficoll and TNP-BA are T-I [thymic independent] antigens. TNP-AECM-Ficoll fails to stimulate in vitro responses by immunologically defective CBA/N and neonatal spleen cells. TNP-BA can cause responses from both these animals. The Ig[immunoglobulin]D receptor is critical to T-I antibody responses initiated by TNP-AECM-Ficoll but it is not required for T-I responses stimulated by TNP-BA.