Psoriasis confined strictly to vitiligo areas – a Koebner‐like phenomenon?

Vitiligo and psoriasis are both common skin disorders. However, psoriasis strictly confined to pre-existing vitiligo areas is rare and suggests a causal relationship. We report here on two patients with a strict anatomical colocalization of vitiligo and psoriasis. The histopathological examinations showed typical changes for both diseases together with a dense infiltrate of CD4+ and CD8+ T cells. By immunohistochemistry, intracytoplasmatic granzyme B and tumour necrosis factor alpha (TNF-alpha) were detected within the T-cell population, suggesting the functional activity of these cells and the creation of a local T helper 1 (Th1)-cytokine milieu. Additionally, in one patient we could identify anti-melanocytic T cells by tetramer staining and enzyme-linked immunospot (ELISPOT) analysis. These skin-infiltrating lymphocytes might trigger, by the local production of Th-1 cytokines such as TNF-alpha and interferon-gamma (IFN-gamma), the eruption of psoriatic plaques in patients with a genetic predisposition for psoriasis.     

Loss of CD8 and TCR binding to Class I MHC ligands following T cell activation

The capacity of T cells to bind peptide/MHC ligands changes with T cell development and differentiation. Here we study changes in peptide/MHC multimer binding following T cell activation. Surprisingly, T cell activation caused a marked reduction in specific peptide/MHC Class I multimer binding, which was distinct from transient TCR down-regulation, and was especially dramatic for engagement with low-affinity peptide/MHC ligands. Direct CD8-Class I interactions were also profoundly and rapidly impaired following T cell stimulation, even though surface CD8alpha and CD8beta levels were unchanged after activation, suggesting that decreased CD8 co-receptor binding contributes to this effect. Finally, we show that enzymatic desialylation restores much of the multimer binding on activated T cells, suggesting that altered glycosylation may inhibit TCR/CD8 binding to peptide/MHC ligands. These radical changes in activated T cells' ability to perceive peptide/MHC ligands may contribute to selective outgrowth of clones with high affinity for the stimulatory ligand.     

Use of class II tetramers for identification of CD4+ T cells

Multivalent MHC class II molecules containing peptide antigens are useful tools for the detection of antigen specific human CD4+ T cells. Tetramers produced by exogenous peptide loading onto empty class II molecules are comparable to tetramers with peptide tethered to the class II chain covalently, but have many practical advantages. Conditions for optimal peptide loading to generate tetramers are discussed and optimal conditions of using tetramers for staining T cells are examined. As the frequency of antigen specific CD4+ T cells in peripheral blood is low, we demonstrate that an in vitro expansion step is effective in detecting low frequency T cells. Two new applications with tetramers, their uses for mapping T cell epitopes and for the detection of low affinity T cells are described. In a clinical setting, potential applications include using these reagents for monitoring disease progression during clinical intervention.     

Functional supertype of HLA-A2 in the presentation of Flu matrix p58-66 to induce CD8+ T-cell response in a Northern Chinese population

The functional supertype of HLA-A2 was investigated in the presentation of the A*0201-restricted Flu matrix p58-66 peptide to activate recall CD8+ T-cell response. In healthy Northern Chinese, the HLA-A2 supertype was mainly composed of the six alleles, A*0201 (26.4%), A*0206 (12.7%), A*0203 (8.2%), A*0207 (7.3%), A*0210 (1.8%) and A*0205 (0.9%), as analyzed by PCR using sequence specific primer (PCR-SSP) and sequence based typing (SBT). The IFN-gamma release Elispot assay was employed to assess effector CD8+ T cells. In A*0201-bearing individuals, the CD8+ T-cell response was potent when stimulated with autologous CD8- PBMCs. The frequency of the effector CD8+ T cells was 96.6% with the magnitude of effector CD8+ T cells of 225 SFC/5 x 104 CD8+ T cells and the RI of 25.7. In non-A*0201 individuals, the effector CD8+ T cells were minimally detectable while the peptide was presented by the autologous CD8- PBMCs. However, the induction of the response of CD8+ T cells obtained from non-A*0201 individuals was remarkably improved when the peptide was presented by autologous dendritic cells instead of CD8- PBMCs. The HLA-A2 alleles possessing cross-reactivity in the peptide presentation were mainly of A*0206 and non-A*0201 heterozygotes of A*0206 and A*0210. Moreover, A*0206 as the HLA-A2 functional supertype was further confirmed by tetramer assay. In two A*0206+ donors with CD8+ T-cell response to the peptide, the CD8+ T-cell frequency assessed by specific binding of peptide HLA-A*0201 tetramer was 4.62% and 1.66%, respectively. Thus, our results have substantiated the immunological relevance of the HLA-A2 supertype, which may benefit the design of peptide vaccines with the potential to be applicable in broader populations.     

Advances in allergen-specific immune cell measurements for improved detection of allergic sensitization and immunotherapy responses

Over the past two decades, precision medicine has advanced diagnostics and treatment of allergic diseases. Component-resolved analysis of allergen sensitization facilitates stratification of patients. Furthermore, new formulations of allergen immunotherapy (AIT) products can more effectively deliver the relevant components. Molecular insights from the identification of allergen component sensitization and clinical outcomes of treatment with new AIT formulations can now be utilized for a deeper understanding of the nature of the pathogenic immune response in allergy and how this can be corrected by AIT. Fundamental in these processes are the allergen-specific B and T cells. Within the large B- and T-cell compartments, only those that specifically recognize the allergen with their immunoglobulin (Ig) or T-cell receptor (TCR), respectively, are of clinical relevance. With peripheral blood allergen-specific B- and T-cell frequencies below 1%, bulk cell analysis is typically insufficiently sensitive. We here review the latest technologies to detect allergen-specific B and T cells, as well as new developments in utilizing these tools for diagnostics and therapy monitoring to advance precision medicine for allergic diseases.     

Viral antigen-specific CD8+ T-cell responses are impaired in multiple myeloma

Multiple myeloma (MM) is associated with defects of humoral and cellular immunity, however, little is known about the frequency and function of antigen-specific CD8+ T cells. Such information might be critical for the development of immunotherapy for MM patients. As a model, we assessed the frequency and proliferation of CD8+ T cells specific for HLA-A*0201-restricted immunodominant epitopes from influenza A (Inf A) and Epstein-Barr virus (EBV). Experiments in identical twins demonstrated reduced numbers of antigen-specific T cells after ex-vivo antigenic challenge in the MM twin when compared with the healthy twin. Similarly, the proliferation and frequency of EBV- and Inf A-specific T cells was also significantly reduced in a cohort of 24 previously untreated or conventionally treated MM patients when compared with 19 healthy individuals. In contrast, MM patients studied after receiving an autologous stem cell transplantation showed strikingly higher frequencies of EBV-specific T cells with potential to proliferate ex vivo, suggesting that EBV-specific T cells are readily expandable under these circumstances. These data identify an impaired response of CD8+ T cells in MM patients, which might in part explain the relatively limited success of anti-MM immunisations. Prospective studies will determine whether such immune assessment strategies may identify patients more likely to benefit from cancer immunotherapy.     

Generation of cytotoxic T lymphocytes specific for the prostate and breast tissue antigen TARP

BACKGROUND: Expansion of cytotoxic T lymphocytes (CTL) directed against peptide epitopes from antigens that are specifically expressed by normal and neoplastic prostate epithelial cells has during the last years emerged as an interesting therapeutic approach to treat advanced prostate cancer. TCRgamma alternate reading frame protein (TARP) is a protein that in males is specifically expressed by normal prostate epithelial cells and prostate cancer cells. We have evaluated TARP for human leukocyte antigen (HLA)-A*0201-restricted peptides capable of triggering TARP-specific CTL. METHODS: Dendritic cells (DC) were pulsed either with synthetic peptides derived from the natural amino acid sequence of TARP or with cognate peptides having enhanced affinity for HLA-A*0201 due to an N-terminal anchor residue substitution. The peptide-pulsed DC were used to stimulate autologous T cells ex vivo. RESULTS: We were able to generate T cells against TARP(27-35) and TARP(4-13) and their mutated counterparts TARP(V28L)(27-35) and TARP(P5L)(4-13). The use of affinity-enhanced peptides resulted in the generation of T cells recognizing target cells displaying either wild-type or mutated peptide. We further show that TARP-specific T cells can be tetramer-sorted and subsequently expanded to large numbers by general T cell stimulation, with retained specificity and activity. Sorted and expanded T cells, obtained by stimulation with TARP(P5L)(4-13), exert moderate lysis of the TARP-expressing prostate cancer cell line, LNCaP, and breast cancer cell line, MCF-7, indicating that the TARP(4-13) epitope may be endogenously processed and presented by TARP-positive, HLA-A*0201-positive cells. CONCLUSIONS: Our findings suggest that synthetic TARP peptides, such as TARP(P5L)(4-13), may play a role in prostate and breast cancer immunotherapy.