Potential of an altered peptide ligand of lipocalin allergen Bos d 2 for peptide immunotherapy.

BACKGROUND: Peptide immunotherapy is a promising alternative for treating allergic diseases. One way to enhance the efficacy of peptide immunotherapy is to use altered peptide ligands (APLs) that contain amino acid substitutions compared with the natural peptide. OBJECTIVE: To evaluate the potential of an APL of the immunodominant epitope of lipocalin allergen Bos d 2 for peptide immunotherapy. METHODS: Peripheral blood CD4(+) T-cell responses of 8 HLA-DR4-positive subjects to the natural ligand of Bos d 2 (p127-142) or to an APL (pN135D) were analyzed by MHC class II tetramer staining after in vitro expansion with the peptides. Long-term T-cell lines (TCLs) were induced with the peptides, and the cytokine production, cross-reactivity, and T-cell receptor Vbeta subtype expression of the TCLs were analyzed. RESULTS: CD4(+) T cells specific for both p127-142 and pN135D were readily detected in peripheral blood after a single in vitro stimulation. Whereas the TCLs induced with p127-142 were T(H)2/T(H)0-deviated, those induced with pN135D were T(H)1/T(H)0-deviated and highly cross-reactive with p127-142. Moreover, the pN135D-induced TCLs appeared to use a broader repertoire of T-cell receptor Vbeta subtypes than those induced with p127-142. CONCLUSION: An APL of an immunodominant allergen epitope was able to induce a novel T(H)1-deviated T-cell population cross-reactive with the natural epitope in vitro. This cell population could have a therapeutic immunomodulatory function in vivo through bystander suppression. CLINICAL IMPLICATIONS: These results support the idea that altered peptide ligands may be used to enhance the efficacy of peptide immunotherapy.

Use of multiple peptides containing T cell epitopes is a feasible approach for peptide-based immunotherapy in Can f 1 allergy.

We have previously shown that the major dog allergen Can f 1 contains seven T cell epitope regions, none of which was preferentially recognized. To identify the immune characteristics of Can f 1 epitopes and to verify their suitability for peptide-based allergen immunotherapy, short-term T cell lines were generated with epitope-containing peptides from peripheral blood mononuclear cells of Can f 1 skinprick test-positive allergic and healthy control subjects. The lines were examined for their proliferative capacity and cytokine production upon stimulation with the allergen peptide, a homologous peptide from human tear lipocalin (TL) and Can f 1 and TL proteins. Can f 1 peptides induced proliferation of T cells and gave rise to T cell lines with comparable efficiencies. In particular, the T cell lines of allergic subjects induced with p33-48 and p107-122 favoured the production of interferon-gamma and interleukin-10, respectively. A greater number of Can f 1-specific T cell lines were generated from allergic than from healthy individuals. Two p107-122-induced Can f 1-specific T cell lines also reacted to a homologous peptide of human TL. Our results suggest that several T cell epitope-containing peptides should be used in combination for specific immunotherapy in Can f 1 allergy.

Immunomodulatory potential of heteroclitic analogs of the dominant T-cell epitope of lipocalin allergen Bos d 2 on specific T cells.

Peptide-based allergen immunotherapy is a novel alternative for conventional allergen immunotherapy. Here, we have characterized the immunomodulatory potential of heteroclitic peptide analogs of the immunodominant epitope of lipocalin allergen Bos d 2 on specific human T-cell clones. The TCR affinity of Bos d 2-specific T-cell clones for the natural peptide ligand and its heteroclitic analogs was assessed with fluorescent-labeled MHC class II tetramers. The activation and cytokine production of the clones were analyzed upon stimulation with the different ligands. Moreover, the capacity of the heteroclitic analogs to induce hyporesponsiveness and cell death was examined. The T-cell clones F1-9 and K3-2 bound MHC class II tetramers loaded with the heteroclitic peptide analogs of the immunodominant epitope of Bos d 2 with increased affinity. At similar peptide concentrations, stimulation of the clones with the heteroclitic analogs favored increased IFN-gamma/IL-4 and IFN-gamma/IL-5 ratios in comparison with stimulation with the natural peptide ligand. Moreover, the T-cell clones stimulated with the heteroclitic analogs exhibited an increased susceptibility to cell death or hyporesponsiveness upon re-stimulation. Our results suggest that heteroclitic analogs of a T-cell epitope of an allergen may enhance the efficacy of peptide-based allergen immunotherapy.

T cell epitope-containing peptides of the major dog allergen Can f 1 as candidates for allergen immunotherapy.

One prerequisite for developing peptide-based allergen immunotherapy is knowing the T cell epitopes of an allergen. In this study, human T cell reactivity against the major dog allergen Can f 1 was investigated to determine peptides suitable for immunotherapy. Seven T cell epitope regions (A-G) were found in Can f 1 with specific T cell lines and clones. The localization of the epitope regions shows similarities with those of the epitopes found in Bos d 2 and Rat n 1. On average, individuals recognized three epitopes in Can f 1. Our results suggest that seven 16-mer peptides (p15-30, p33-48, p49-64, p73-88, p107-122, p123-138, and p141-156), each from one of the epitope regions, show widespread T cell reactivity in the population studied, and they bind efficiently to seven HLA-DRB1 molecules (DRB1*0101, DRB1*0301, DRB1*0401, DRB1*0701, DRB1*1101, DRB1*1301, and DRB1*1501) predominant in Caucasian populations. Therefore, these peptides are potential candidates for immunotherapy of dog allergy.

Effects of short- and long-term ultraviolet B irradiation on the immune system of the common carp (Cyprinus carpio).

Carp (Cyprinus carpio) were repeatedly exposed to 0, 60, 120 and 240 mJ/cm2 ultraviolet B (UVB) radiation three times in 1 week (short-term exposure) or 12 times in 4 weeks (long-term exposure). The effect of UVB on the functioning of the carp immune system was studied on day 2 after the final irradiation. After short-term UVB exposure, the whole-blood respiratory burst and cytotoxic activity were markedly enhanced, with parallel responses in both the number of circulating granulocytes and in the plasma cortisol concentration of the fish. These changes were not detectable after long-term exposure. The respiratory burst by head kidney granulocytes was suppressed dose dependently after both exposures, but cytotoxic activity was not affected. Exposure to UVB also modulated lymphocyte functions: nonstimulated and PHA-stimulated proliferation of head kidney lymphocytes in vitro was enhanced by both short-term and long-term exposure. LPS-stimulated proliferation was not affected by exposure nor was the number of immunoglobulin-secreting cells in the head kidney. In long-term exposure, the highest dose reduced the level of plasma IgM. This study indicates that UVB irradiation induces immunomodulation in the blood and head kidney of the carp and that the effects of short- and long-term exposure differ from each other. The results emphasize the potentially harmful impact of increased solar UVB radiation on fish immune functions.