Cutting edge: the HLA-A*0101-restricted HY minor histocompatibility antigen originates from DFFRY and contains a cysteinylated cysteine residue as identified by a novel mass spectrometric technique.

In this report, we describe the use of novel mass spectrometry instrumentation to identify a male-specific minor histocompatibility Ag restricted by HLA-A*0101 (A1-HY). This Ag has the sequence IVDC*LTEMY, where C* represents a cysteine disulfide bonded to a second cysteine residue. The core peptide sequence is found in the protein product of DFFRY, a Y chromosome gene not previously identified as the source of an HY Ag. The male-specific form of the peptide differs from its X chromosomal counterpart by the substitution of serine for the C* residue. Both peptides are expressed on the cell surface at 30 or fewer copies per cell. However, A1-HY-specific CTL recognize the DFFRY-derived peptide at a 1500-fold lower dose than the female homologue. Thus, these studies have identified a new source of HY epitopes and provide additional information about the influence of posttranslational modifications of class I-associated peptides on T cell recognition.

Characteristics of Prevotella intermedia-specific CD4+ T cell clones from peripheral blood of a chronic adult periodontitis patient.

Periodontitis is a chronic destructive inflammatory disease associated with periodontopathic bacteria. In addition, autoantigens such as collagen and heat shock proteins (hsp) have been suggested to play a role. Established periodontal lesions are characterized by dense infiltrations of immune cells such as cytokine-producing CD4+ and CD8+ T cells. CD4+ T cells specific for Prevotella intermedia can be isolated from lesional gingiva, suggesting an active role for CD4+ T cells in the response to this bacterium. We therefore investigated the characteristics of a panel of 13 P. intermedia-specific CD4+ T cells generated from the peripheral blood of a patient with chronic adult periodontitis. All 13 P. intermedia-specific CD4+ T cells recognized the antigens in the context of HLA-DR. The T cell clones were mainly classified as Th0, producing comparable amounts of interferon-gamma (IFN-gamma) and IL-4, and Th2, producing high amounts of IL-4 and almost no IFN-gamma. None of the P. intermedia-specific T cell clones recognized antigens of the periodontopathic bacteria Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis and of the autoantigens collagen and hsp. The reactivity profile of the T cell clones to size-fractionated cell envelope antigens of P. intermedia indicated that P. intermedia-specific CD4+ T cell clones recognize probably five different antigen specificities in the context of the MHC class II molecules, DR7 or DR15. These results suggest that a broad panel of cell-associated protein antigens play a role in the induction of P. intermedia-specific CD4+ T cell response.

The minor histocompatibility antigen HA-1: a diallelic gene with a single amino acid polymorphism.

The minor histocompatibility antigen (mHag) HA-1 is the only known mHag for which mismatching is correlated with the development of severe graft versus host disease (GvHD) after human leukocyte antigen-identical bone marrow transplantation. HA-1 was found to be a nonapeptide derived from an allele of the KIAA0223 gene. The HA-1-negative allelic counterpart encoded by KIAA0223 had one amino acid difference from HA-1. Family analysis with HA-1 allele-specific polymerase chain reaction showed an exact correlation between this allelic polymorphism and the HA-1 phenotype. HA-1 allele typing of donor and recipient should improve donor selection and allow the determination of bone marrow transplantation recipients with high risk for HA-1-induced GvHD development.

The HLA-A*0201-restricted H-Y antigen contains a posttranslationally modified cysteine that significantly affects T cell recognition.

A peptide recognized by two cytotoxic T cell clones specific for the human minor histocompatibility antigen H-Y and restricted by HLA-A*0201 was identified. This peptide originates from SMCY, as do two other H-Y epitopes, supporting the importance of this protein as a major source of H-Y determinants in mice and humans. In naturally processed peptides, T cells only recognize posttranslationally altered forms of this peptide that have undergone modification of a cysteine residue in the seventh position. One of these modifications involves attachment of a second cysteine residue via a disulfide bond. This modification has profound effects on T cell recognition and also occurs in other class I MHC-associated peptides, supporting its general importance as an immunological determinant.

Type-1 and type-2 CD8+ T-cell subsets isolated from chronic adult periodontitis tissue differ in surface phenotype and biological functions.

Cloning of CD8+ T cells expressing the alpha beta T-cell receptor from inflamed human gingiva revealed that at least two different subsets were found within the tissue and that these subsets were able to interact with each other. One subset produced high levels of interferon-gamma (IFN-gamma) and no interleukin-4 (IL-4) or IL-5, exhibited phytohaemagglutinin (PHA)- or anti-CD3-mediated cytolytic activity, and were CD28+. The other subset produced high levels of IL-4 in combination with IL-5, displayed no cytotoxicity and were CD28-. From the latter subset CD8+ T-cell clones were able to suppress the proliferative response of cytotoxic CD8+ T-cell clones. This suppression could be abolished by anti-IL-4 monoclonal antibodies. However, IL-4 alone was not able to induce the suppression. Our results indicate that CD8+ T cells might participate in local immune responses by the suppression of IFN-gamma-producing cells and by favouring humoral responses via the production of IL-4 and IL-5.

Cloning, characterization, and antigen specificity of T-lymphocyte subsets extracted from gingival tissue of chronic adult periodontitis patients.

Chronic periodontitis is characterized by dense infiltrations of B and T lymphocytes within the gingival connective tissue. Distinct anaerobic gram-negative bacteria as well as autoimmunity to collagen have been reported to play a role in the etiology and the pathogenesis of this disease. Here we describe the cloning and characterization of CD4+ and CD8+ T lymphocytes isolated from inflamed gingival tissue obtained from four patients with chronic periodontitis. Clones were raised with phytohemagglutinin and interleukin-2 and tested for proliferation in response to whole-cell antigens of Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, human collagen type I, and two bacterial heat shock proteins. CD4+ T-cell clones reactive with collagen type I were obtained from all four patients. Eighty percent of these clones had phenotypes resembling the mouse type 2 T helper (Th) phenotype, i.e., they produced high levels of interleukin-4 and low levels of gamma interferon. No collagen-type-I-reactive CD8+ clones were obtained. Bacterial-antigen-reactive CD4+ and/or CD8+ T-cell clones were also obtained from each patient, and the majority of the clones showed a Th0-like cytokine pattern and produced equal amounts of interleukin-4 and gamma interferon. Although most clones were reactive with P. intermedia, it seems that the immune response is not strictly directed against this particular microorganism, as clones reactive with one of the other bacteria were also obtained from two patients. We propose that collagen-specific CD4+ Th2-like T cells contribute to the chronicity of periodontitis but that their modes of activation might be controlled by Th0-like T cells specific for periodontitis-associated bacteria.