Quantitation of Anaplasma marginale major surface protein (MSP)1a and MSP2 epitope-specific CD4+ T lymphocytes using bovine DRB31101 and DRB31201 tetramers

• Published in: Immunogenetics (New York) Vol. 58; no. 9; pp. 726 - 739
• Main Authors: Norimine, Junzo, Han, Sushan, Brown, Wendy C
• Format: Journal Article
• Language: English
• Published: United States Springer Nature B.V 01.09.2006
• Subjects: Amino Acid Sequence; Anaplasma marginale - genetics; Anaplasma marginale - immunology; Anaplasma marginale - pathogenicity; Animals; Antigens, Bacterial - genetics; Antigens, Bacterial - immunology; Bacterial Outer Membrane Proteins - genetics; Bacterial Outer Membrane Proteins - immunology; Base Sequence; Cattle; CD4-Positive T-Lymphocytes - immunology; Cell Line; DNA - genetics; Erythrocytes - immunology; Erythrocytes - microbiology; Genes, MHC Class II; Histocompatibility Antigens Class II - chemistry; Histocompatibility Antigens Class II - genetics; Immune response; Immunization; Immunodominant Epitopes - genetics; Immunology; In Vitro Techniques; Lymphocytes; Medical research; Molecular Sequence Data; Pathogens; Peptides; Protein Structure, Quaternary; Transfection
• ISSN: 0093-7711; 1432-1211
• DOI: 10.1007/s00251-006-0140-3

Antigen-specific CD4+ T cells play a critical role in protective immunity to many infectious pathogens. Although the antigen-specific CD4+ T cells can be measured by functional assays such as proliferation or cytokine enzyme-linked immunospot, such assays are limited to a specific function and cannot quantify anergic or suppressed T cells. In contrast, major histocompatiblity complex (MHC) class II tetramers can enumerate epitope-specific CD4+ T cells independent of function. In this paper, we report the construction of bovine leukocyte antigen MHC class II tetramers using a novel mammalian cell system to express soluble class II DRA/DRB3 molecules and defined immunodominant peptide epitopes of Anaplasma marginale major surface proteins (MSPs). Phycoerythrin-labeled tetramers were either loaded with exogenous peptide or constructed with the peptide epitope linked to the N terminus of the DRB3 chain. A DRB3*1101 tetramer loaded with MSP1a peptide F2-5B (ARSVLETLAGHVDALG) and DRB3*1201 tetramers loaded with MSP1a peptide F2-1-1b (GEGYATYLAQAFA) or MSP2 peptide P16-7 (NFAYFGGELGVRFAF) specifically stained antigen-specific CD4+ T cell lines and clones. Tetramers constructed with the T-cell epitope linked to the DRB3 chain were slightly better at labeling CD4+ T cells. In one cell line, the number of tetramer-positive T cells increased to approximately 94% of the CD4+ T cells after culture for 21 weeks with specific antigen. This novel technology should be useful to track the fate of antigen-specific CD4+ T-cell responses in cattle after immunization or infection with persistent pathogens, such as A. marginale, that modulate the host immune response.