Immunoglobulin epitopes defined by synthetic peptides corresponding to joining region sequence: conservation of determinants and dependence upon the presence of an arginyl or lysyl residue for cross-reaction between light chains and T-cell receptor chains.
Joining or J region sequences of rearranging immunoglobulins and T-cell receptors show considerable sequence homology, particularly in their C-terminal portion corresponding to the fourth framework region of immunoglobulin variable regions. In order to test the question of whether serological cross-reactions between immunoglobulin variable regions and T-cell receptors were due to antigenic similarities in their J regions, we synthesized synthetic peptides corresponding to immunoglobulin J regions and to J regions predicted from gene sequence of the T-cell receptor beta chain. We found that antibodies produced against a synthetic 16-mer J beta sequence reacted with T-cell receptor chains and also with immunoglobulin light chains. The cross-reactivity was dependent upon the J signature sequence FG()GT(R or K)L where the presence of a positively charged lysyl or arginyl residue was essential for cross-reactivity. We were able to classify J region determinants into two distinct antigenic sets; one corresponding to JH and the other corresponding to J kappa, J lambda, J beta and J alpha. Although considerable homology occurs between JH and JL (or J beta) sequences, little cross-reactivity was observed between these two J subsets. Antibodies raised against polyclonal murine IgG immunoglobulins contained antibody subpopulations specifically reactive with either JH or J beta peptides. The serological data derived here using antipeptide antibodies are consistent with computer modeling studies that indicate that the conformations of T-cell receptor variable regions resemble those of classical immunoglobulins. Our data comparing cross-reactivities restricted to the J region indicate that the expression of the J region by intact T-cell receptor beta chains is probably more similar to that of light chains than it is to the corresponding region of heavy chains.
Marchalonis
J J
JJ
Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston 29425.
Schluter
S F
SF
Hubbard
R A
RA
McCabe
C
C
Allen
R C
RC
D000818:Animals; D000918:Antibody Specificity; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000032:analysis*; D007143:Immunoglobulin Heavy Chains / Q000276:immunology; D007133:Immunoglobulin Joining Region / Q000276:immunology*; D007147:Immunoglobulin Light Chains / Q000276:immunology*; D007135:Immunoglobulin Variable Region / Q000276:immunology; D010455:Peptides / Q000138:chemical synthesis; D011817:Rabbits; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*
D000939:Epitopes; D007143:Immunoglobulin Heavy Chains; D007133:Immunoglobulin Joining Region; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D010455:Peptides; D011948:Receptors, Antigen, T-Cell