Epitope specificity of bee venom phospholipase A2-specific suppressor T cells which produce antigen-binding glycosylation inhibiting factor

• Published in: International immunology 1993-08, Vol.5 (8), p.833-842
• Main Authors: Mori, Akio, Thomas, Peter, Tagaya, Yutaka, Iijima, Hiroshi, Grey, Howard, Ishizaka, Kimishige
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Analysis of the immune response. Humoral and cellular immunity; Animals; Antigens - immunology; bee venom; Bee Venoms - immunology; Biological and medical sciences; Epitopes; Fundamental and applied biological sciences. Psychology; Fundamental immunology; GIF; Glycosylation; Hybridomas; Immunobiology; Lymphokines - biosynthesis; Lymphokines - immunology; Mice; Mice, Inbred BALB C; Molecular Sequence Data; Organs and cells involved in the immune response; Peptide Fragments - immunology; Phospholipases A - immunology; Phospholipases A2; PLA2; Prostatic Secretory Proteins; Receptors, Antigen, T-Cell - immunology; Suppressor Factors, Immunologic - biosynthesis; suppressor T cells; T-Lymphocytes, Regulatory - immunology
• ISSN: 0953-8178; 1460-2377
• DOI: 10.1093/intimm/5.8.833

From the spleen cells of BALB/c mice primed with bee venom phospholipase A2(PLA2), we established seven T cell hybrldomas which constitutively secreted glycosylation inhibiting factor (GIF), expressed both CD3 and TCRαβ, 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 antl-TCRα 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 antigenbinding GIF upon antigenic stimulation recognized the synthetic peptide representing amino acid residues 19–34 in PLA2molecules 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 moiecule and represents an external structure of the antigen, while peptide 25–37 forms an α helix. Evidence was obtained which suggests that the sequence of 25–34 contains amino acid residues interacting with la molecules, while peptide 19–24 contains residues involved in the interaction of p19–34-la 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.