Immunoglobulin-specific T-B cell interaction. II. T cell clones recognize the processed form of B cells' own surface immunoglobulin in the context of the major histocompatibility complex class II molecule.
In the preceding report (Eur. J. Immunol. 1989. 19: 1677) we have demonstrated that normal B cells, including small B cells, are capable of presenting Ig kappa-1b allotypic determinants of their endogeneously synthesized Ig+ to Ig kappa-1b-immune major histocompatibility complex (MHC) class II-restricted T cells. A panel of Ig kappa-1b allotype-specific T cell clones from August rats has been developed to study further the presentation of self surface Ig by B cells from Ig kappa-1-congeneic August.1b rats. All the clones studied were of the T helper/inducer phenotype (W3/25+,OX8-) and restricted by the RT-1Bc molecule. These clones responded both to the serum IgG(Ig kappa-1b) in the presence of irradiated spleen cells (SC) from August rats and to the Ig kappa-1b-bearing irradiated B cells from August.1b rats. SC presentation of secreted IgG was much less effective than B cell presentation of membrane Ig. Using CNBr cleavage of isolated C kappa (Ig kappa-1b) domain followed by high-performance liquid chromatography fractionation of the derived antigenic peptides, the kappa chain sequence between amino acids 176 and 214 has been identified as the T cell epitope recognized by all T cell clones in association with RT-1Bc. The fragment 176-214 of the Ig kappa-1b allotype differs from that of Ig kappa-1a allotype by three amino acid substitutions at positions 184, 185, 188. T cell recognition of pL kappa-1b(176-214) required no additional processing by the antigen-presenting cell: the efficient presentation of the peptide but not of intact IgG(Ig kappa-1b) by the paraformaldehyde-fixed SC was observed. These data provide clear-cut evidence for an absolute requirement of the processing of Ig molecules for T cell recognition to occur in our experimental system. Although the fixation of B cells from August.1b rats diminished their Ig kappa-1b-presenting ability, fixed Ig kappa-1b+ B cells were still able to induce Ig kappa-1b-specific T cell clone responses. Our results suggest that B cells can express the processed form of self-synthesized surface Ig in addition to intact surface Ig molecules. The former can be recognized by MHC-restricted T cell.
Yurin
V L
VL
Laboratory of Immunology, All-Union Research Institute for Genetics, Moscow, USSR.
Rudensky
A Y
AY
Mazel
S M
SM
Blechman
J M
JM
D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D002999:Clone Cells; D000949:Histocompatibility Antigens Class II / Q000502:physiology*; D007126:Immunoglobulin Allotypes / Q000276:immunology; D007145:Immunoglobulin kappa-Chains / Q000276:immunology*; D008211:Lymphocyte Cooperation; D008285:Major Histocompatibility Complex; D010047:Ovalbumin / Q000276:immunology; D010446:Peptide Fragments / Q000276:immunology; D051381:Rats; D011919:Rats, Inbred Strains; D011947:Receptors, Antigen, B-Cell / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D014373:Tuberculin / Q000276:immunology
D000949:Histocompatibility Antigens Class II; D007126:Immunoglobulin Allotypes; D007145:Immunoglobulin kappa-Chains; D010446:Peptide Fragments; D011947:Receptors, Antigen, B-Cell; D014373:Tuberculin; D010047:Ovalbumin