Epitope specificity of bee venom phospholipase A2-specific suppressor T cells which produce antigen-binding glycosylation inhibiting factor.
From the spleen cells of BALB/c mice primed with bee venom phospholipase A2 (PLA2), we established seven T cell hybridomas which constitutively secreted glycosylation inhibiting factor (GIF), expressed both CD3 and TCR alpha beta, and responded to antigen-pulsed antigen presenting cells (APC) for the formation of IgE-binding factor. Upon stimulation with antigen-pulsed APC, four of the seven hybridomas produced GIF having affinity for native PLA2. The antigen-binding GIF could suppress the anti-hapten antibody response of BALB/c mice to dinitrophenyl (DNP)-PLA2 conjugates in a carrier-specific manner and bound to immunosorbents coupled with either the mAb 14-12 or anti-TCR alpha chain, H28-710. Analysis of the epitope specificity of the TCR on the GIF-producing T hybridomas indicated that all of the hybridomas which could produce antigen-binding GIF upon antigenic stimulation recognized the synthetic peptide representing amino acid residues 19-34 in PLA2 molecules in the context of the product of the I-Ad subregion and the antigen-binding GIF formed by the cells had affinity for the peptide. The 3-D structure of bee venom PLA2 indicates that the sequence of amino acid 14-24 forms a loop in the PLA2 molecule and represents an external structure of the antigen, while peptide 25-37 forms an alpha helix. Evidence was obtained which suggests that the sequence of 25-34 contains amino acid residues interacting with Ia molecules, while peptide 19-24 contains residues involved in the interaction of p19-34-Ia complexes with TCR on the hybridomas. It was also found that not only the synthetic peptide 19-34, but also the peptides 13-28 and 19-30 inhibited the binding of antigen-binding GIF to PLA2-coupled Sepharose, while peptide 25-40 failed to do so. The results collectively indicate that the antigen-binding GIF and TCR on the cell source of the factor interact with a common epitope which is exposed on the surface of a nominal antigen.
Mori
A
A
Division of Immunobiology, La Jolla Institute for Allergy and Immunology, CA 92037.
Thomas
P
P
Tagaya
Y
Y
Iijima
H
H
Grey
H
H
Ishizaka
K
K
D000595:Amino Acid Sequence; D000818:Animals; D000941:Antigens / Q000276:immunology; D001514:Bee Venoms / Q000276:immunology*; D000939:Epitopes; D006031:Glycosylation; D006825:Hybridomas; D008222:Lymphokines / Q000096:biosynthesis* / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology; D010741:Phospholipases A / Q000276:immunology*; D054467:Phospholipases A2; D029584:Prostatic Secretory Proteins; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D013491:Suppressor Factors, Immunologic / Q000096:biosynthesis*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
D000941:Antigens; D001514:Bee Venoms; D000939:Epitopes; D008222:Lymphokines; D010446:Peptide Fragments; D029584:Prostatic Secretory Proteins; D011948:Receptors, Antigen, T-Cell; D013491:Suppressor Factors, Immunologic; C043076:beta-microseminoprotein; C013059:immunoglobulin-binding factors; D010741:Phospholipases A; D054467:Phospholipases A2