HLA-DPB1 Mismatching Results in the Generation of a Full Repertoire of HLA-DPB1-Specific CD4⁺ T Cell Responses Showing Immunogenicity of all HLA-DPB1 Alleles

Differential crossrecognition of HLA-DPB1 molecules by CD4⁺ T cell clones with the same HLA-DPB1 specificity. Different HLA-DPB1^∗0201 (n = 5), ^∗0301 (n = 6), or ^∗0401 (n = 5)-specific CD4⁺ T cell clones, identified by different TCR-Vβ expression, were tested for recognition of 12 different HLA-DPB1 transduced HeLa-II cell lines. Each row represents recognition of the 12 different HLA-DPB1 molecules by 1 CD4⁺ T cell clone. Overnight IFN-γ production measured in 50 μL supernatant is shown (pg/mL). “- “ indicates <100 pg/mL IFN-γ measured. (A) HLA-DPB1^∗0201-specific CD4⁺ T cell clones were isolated during clinical immune response to DLI from an HLA-DPB1^∗0402, 0501 typed donor. (B) HLA-DPB1^∗0301-specific CD4⁺ T cell clones isolated clinical immune response to DLI from an HLA-DPB1^∗0402, 0501 typed donor. (C) HLA-DPB1^∗0401-specific CD4⁺ T cell clones isolated during the clinical immune response to DLI from an HLA-DPB1^∗0301, 0402 typed donor.

In vitro generation of an HLA-DPB1^∗03-specific CD4⁺ T cell line. (A) CD4⁺ T cells purified from an HLA-DPB1^∗0402, 0501 typed responder were stimulated with HeLa-II cells transduced with HLA-DPB1^∗0301. At day 14, CD4⁺ T cells were tested for recognition of untransduced HeLa-II cells or responder EBV-LCL and HeLa-II cells or responder EBV-LCL transduced with HLA-DPB1^∗03 or random control HLA-DPB1^∗02. IFN-γ release (pg/mL) in 50 μL supernatant is shown after overnight incubation with different stimulator cells. (B) IFN-γ production from 24 HLA-DPB1^∗03-specific CD4⁺ T cell clones in response to different stimulators was determined in 50 μL supernatant. Recognition pattern shown in black bars was observed for 19 CD4⁺ T cell clones, whereas the recognition pattern shown by the white bars was observed for 5 CD4⁺ T cell clones.

Comparable HLA-DPB1-specific immune response generated against HLA-DPB1 molecules classified in 4 different groups. (A) Purified CD4⁺ T cells derived from a healthy HLA-DPB1^∗0301 typed individual were stimulated with HeLa-II cells transduced with HLA-DPB1^∗1701, ^∗1401, ^∗0201, or ^∗0401. At day 14, 25,000 CD4⁺ T cells from each cell line were restimulated with 50,000 HLA-DPB1-transduced HeLa-II cells used for stimulation (■) or HeLa-II cells transduced with control responder HLA-DPB1^∗0301 molecules (□). IFN-γ release (pg/mL) measured in 50 μL supernatant upon restimulation is shown. (B) IFN-γ production of the 4 different HLA-DPB1-specific CD4⁺ T cell lines in response to HLA-DPB1-transduced HeLa-II cells used for stimulation is shown using different numbers of responder cells. IFN-γ release was determined in 50-μL supernatant following overnight incubation using 25,000, 10,000, or 2000 responder cells. Immune responses generated against different HLA-DPB1 molecules are depicted using different symbols and lines. (C) Recognition of 2 representative HLA-DPB1^∗1401-specific CD4⁺ T cell clones in response to HeLa cells transduced with HLA-DPB1^∗1401 combined with different HLA-DPA1 molecules. Specificity for HLA-DPB1^∗14 of the CD4⁺ T cell clones is shown by recognition of responder EBV-LCL transduced with HLA-DPB1^∗14. IFN-γ production in 50-μL supernatant was determined by ELISA.

HLA-DPB1-specific immune responses can be generated from all HLA-DPB1 mismatch combinations. Purified CD4⁺ T cells derived from 4 different responders were stimulated with HeLa-II cells transduced with 12 different HLA-DPB1 molecules. At day 14, 25,000 CD4⁺ T cells from each cell line were restimulated with 50,000 HLA-DPB1-transduced HeLa-II cells used for stimulation (■), HeLa-II cells transduced with autologous responder HLA-DPB1 (), or HeLa-II cells without HLA-DP expression (□). IFN-γ release (pg/mL) measured in 50-μL supernatant upon restimulation is shown.

Crossrecognition of 12 different HLA-DPB1 molecules by HLA-DPB1-specific CD4⁺ T cells. Twelve CD4⁺ T cell lines specific for 12 different HLA-DPB1 alleles were tested for recognition of HeLa-II cells transduced with 12 different HLA-DPB1 molecules. Each row in 1 figure represents recognition of the 12 different HLA-DPB1 molecules by 1 CD4⁺ T cell line. Gray boxes represent recognition of the specific HLA-DPB1 molecule used for stimulation for each CD4⁺ T cell line. “++” indicates more than 100 pg/mL IFN-γ production in 50-μL supernatant by 10,000 CD4⁺ T cells upon restimulation with a specific HLA-DPB1 transduced HeLa-II cell line. “+” indicates more than 100 pg/mL IFN-γ production in 50-μL supernatant by 25,000 CD4⁺ T cells upon restimulation with a specific HLA-DPB1-transduced HeLa-II cell line. (A) Results of 12 different HLA-DPB1-specific CD4⁺ T cell lines generated from an HLA-DPB1^∗0301 typed responder. (B) Results of 12 different HLA-DPB1-specific CD4⁺ T cell lines generated from an HLA-DPB1^∗0401 typed responder.