RESUMO
CD4 expression identifies a subset of mature T cells primarily assisting the germinal center reaction and contributing to CD8+ T-cell and B-cell activation, functions, and longevity. Herein, we present a family in which a novel variant disrupting the translation-initiation codon of the CD4 gene resulted in complete loss of membrane and plasma soluble CD4 in peripheral blood, lymph node, bone marrow, skin, and ileum of a homozygous proband. This inherited CD4 knockout disease illustrates the clinical and immunological features of a complete deficiency of any functional component of CD4 and its similarities and differences with other clinical models of primary or acquired loss of CD4+ T cells. The first inherited loss of any functional component of CD4, including soluble CD4, is clinically distinct from any other congenital or acquired CD4 T-cell defect and characterized by compensatory changes in T-cell subsets and functional impairment of B cells, monocytes, and natural killer cells.
Assuntos
Antígenos CD4/deficiência , Antígenos CD4/genética , Síndromes de Imunodeficiência/genética , Iniciação Traducional da Cadeia Peptídica/genética , Doenças da Imunodeficiência Primária/genética , Medula Óssea/imunologia , Medula Óssea/metabolismo , Antígenos CD4/análise , Antígenos CD4/sangue , Linfócitos T CD4-Positivos/imunologia , Códon de Iniciação , Citocinas/imunologia , Citocinas/metabolismo , Feminino , Humanos , Íleo/imunologia , Íleo/metabolismo , Imunidade Inata , Síndromes de Imunodeficiência/imunologia , Células Matadoras Naturais/imunologia , Linfonodos/imunologia , Linfonodos/metabolismo , Ativação Linfocitária , Masculino , Monócitos/imunologia , Mutação de Sentido Incorreto , Linhagem , Doenças da Imunodeficiência Primária/imunologia , Subpopulações de Linfócitos T/imunologia , Adulto JovemRESUMO
Idiopathic T-CD4 lymphocytopenia (ICL) is a rare and heterogeneous syndrome characterized by opportunistic infections due to reduced CD4 T-lymphocytes (<300 cells/µl or <20% T-cells) in the absence of HIV infection and other primary causes of lymphopenia. Molecular testing of ICL has revealed defects in genes not specific to CD4 T-cells, with pleiotropic effects on other cell types. Here we report for the first time an absolute CD4 lymphocytopenia (<0.01 CD4+ T-cells/µl) due to an autosomal recessive CD4 gene mutation that completely abrogates CD4 protein expression on the surface membrane of T-cells, monocytes, and dendritic cells. A 45-year-old female born to consanguineous parents consulted because of exuberant, relapsing, and treatment-refractory warts on her hands and feet since the age of 10 years, in the absence of other recurrent infections or symptoms. Serological studies were negative for severe infections, including HIV 1/2, HTLV-1, and syphilis, but positive for CMV and EBV. Blood analysis showed the absence of CD4+ T-cells (<0.01%) with repeatedly increased counts of B-cells, naïve CD8+ T-lymphocytes, and particularly, CD4/CD8 double-negative (DN) TCRαß+ TCRγδ- T-cells (30% of T-cells; 400 cells/µl). Flow cytometric staining of CD4 using monoclonal antibodies directed against five different epitopes, located in two different domains of the protein, confirmed no cell surface membrane or intracytoplasmic expression of CD4 on T-cells, monocytes, and dendritic cells but normal soluble CD4 plasma levels. DN T-cells showed a phenotypic and functional profile similar to normal CD4+ T-cells as regards expression of maturation markers, T-helper and T-regulatory chemokine receptors, TCRvß repertoire, and in vitro cytokine production against polyclonal and antigen-specific stimuli. Sequencing of the CD4 gene revealed a homozygous (splicing) mutation affecting the last bp on intron 7-8, leading to deletion of the juxtamembrane and intracellular domains of the protein and complete abrogation of CD4 expression on the cell membrane. These findings support previous studies in CD4 KO mice suggesting that surrogate DN helper and regulatory T-cells capable of supporting antigen-specific immune responses are produced in the absence of CD4 signaling and point out the need for better understanding the role of CD4 on thymic selection and the immune response.
Assuntos
Antígenos CD4/deficiência , Antígenos CD4/genética , Mutação , T-Linfocitopenia Idiopática CD4-Positiva/genética , T-Linfocitopenia Idiopática CD4-Positiva/imunologia , Verrugas/genética , Verrugas/imunologia , Antígenos CD4/sangue , Linfócitos T CD4-Positivos/classificação , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/patologia , Linhagem da Célula/genética , Linhagem da Célula/imunologia , Consanguinidade , Citotoxicidade Imunológica , Células Dendríticas/imunologia , Feminino , Genes Recessivos , Homozigoto , Humanos , Imunidade Humoral , Imunidade Inata , Imunofenotipagem , Masculino , Pessoa de Meia-Idade , Monócitos/imunologia , Linhagem , T-Linfocitopenia Idiopática CD4-Positiva/patologia , Verrugas/patologiaRESUMO
BACKGROUND: CD4 T cells have been implicated in the pathology of lymphedema. Interestingly, however, there have been case reports of lymphedema development in patients with low levels of CD4 T cells because of immunosuppression. In this study, the authors sought to delineate the effect of relative CD4 T-cell deficiency on the development of lymphedema in a mouse model. METHODS: A mouse model of relative CD4 T-cell deficiency was created through lethal total body irradiation of wild-type mice that then underwent bone marrow transplantation with progenitors harvested from CD4 knockout mice (wild-type/CD4 knockout). Irradiated CD4 knockout mice reconstituted with wild-type mouse-derived progenitors (CD4 knockout/wild-type), and unirradiated CD4 knockout and wild-type mice were used as controls. All mice underwent tail skin and lymphatic excision to induce lymphedema, and analysis was performed 6 weeks later. RESULTS: Wild-type/CD4 knockout chimeras were not protected from developing lymphedema. Despite a global deficit in CD4 T cells, these mice had swelling, fibrosis, inflammation, and impaired lymphatic transport function indistinguishable from that in wild-type and CD4 knockout/wild-type mice. In contrast, unirradiated CD4 knockout mice had no features of lymphedema after lymphatic injury. CONCLUSIONS: Relatively small numbers of bone marrow and peripheral CD4 T cells are sufficient to induce the development of lymphedema. These findings suggest that lymphatic injury results in expansion of CD4 T-cell populations in lymphedematous tissues.
Assuntos
Antígenos CD4/deficiência , Linfócitos T CD4-Positivos/imunologia , Linfedema/imunologia , Animais , Transplante de Medula Óssea , Antígenos CD4/genética , Antígenos CD4/imunologia , Linfócitos T CD4-Positivos/efeitos da radiação , Modelos Animais de Doenças , Feminino , Humanos , Vasos Linfáticos/patologia , Vasos Linfáticos/cirurgia , Linfedema/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Quimeras de Transplante , Irradiação Corporal TotalRESUMO
In vivo antigen targeting to dendritic cells (DCs) has been used as a way to improve immune responses. Targeting is accomplished with the use of monoclonal antibodies (mAbs) to receptors present on the DC surface fused with the antigen of interest. An anti-DEC205 mAb has been successfully used to target antigens to the DEC205+CD8α+ DC subset. The administration of low doses of the hybrid mAb together with DC maturation stimuli is able to activate specific T cells and induce production of high antibody titres for a number of different antigens. However, it is still not known if this approach would work with any fused protein. Here we genetically fused the αDEC205 mAb with two fragments (42-kDa and 19-kDa) derived from the ~200 kDa Plasmodium vivax merozoite surface protein 1 (MSP1), known as MSP142 and MSP119, respectively. The administration of two doses of αDEC-MSP142, but not of αDEC-MSP119 mAb, together with an adjuvant to two mouse strains induced high anti-MSP119 antibody titres that were dependent on CD4+ T cells elicited by peptides present in the MSP133 sequence, indicating that the presence of T cell epitopes in antigens targeted to DEC205+ DCs increases antibody responses.
Assuntos
Formação de Anticorpos/fisiologia , Células Dendríticas/imunologia , Epitopos de Linfócito T/imunologia , Lectinas Tipo C/imunologia , Sequência de Aminoácidos , Animais , Anticorpos Monoclonais/genética , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/metabolismo , Antígenos CD4/deficiência , Antígenos CD4/genética , Linfócitos T CD4-Positivos/citologia , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Proliferação de Células , Células Dendríticas/citologia , Células Dendríticas/metabolismo , Ensaio de Imunoadsorção Enzimática , Epitopos de Linfócito T/genética , Epitopos de Linfócito T/metabolismo , Feminino , Imunoglobulina G/imunologia , Imunoglobulina G/metabolismo , Interferon gama/metabolismo , Interleucina-2/metabolismo , Proteína 1 de Superfície de Merozoito/química , Proteína 1 de Superfície de Merozoito/genética , Proteína 1 de Superfície de Merozoito/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/imunologia , Baço/citologia , Baço/metabolismo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Peroxisome proliferator-activated receptor gamma (PPARγ), a master regulator of adipocyte differentiation, has recently been connected with effector T cells, though its role is still not clear. Here, we investigated the roles of PPARγ in follicular helper T (TFH) cell responses regarding gender specificity. NP-OVA immunization in female but not male CD4-PPARγ(KO) mice induced higher proportions of TFH cells and germinal center (GC) B cells following immunization than were seen in wild type mice. Treatment with the PPARγ agonist pioglitazone significantly reduced TFH cell responses in female mice while pioglitazone and estradiol (E2) co-treatment ameliorated TFH cells and GC responses in male mice. E2 treatment significantly enhanced PPARγ expression in male T cells, while T cell activation in the estrus but not in the diestrus stage of the menstrual cycle of females was inhibited by pioglitazone, suggesting that an estrogen-sufficient environment is important for PPARγ-mediated T cell regulation. These results demonstrate gender-based differences in sensitivities of PPARγ in TFH responses. These findings suggest that appropriate function of PPARγ is required in the regulation of female GC responses and that therapeutic strategies for autoimmune diseases using PPARγ agonists need to be tailored accordingly.
Assuntos
Estradiol/farmacologia , Ativação Linfocitária/efeitos dos fármacos , PPAR gama/metabolismo , Animais , Linfócitos B/citologia , Linfócitos B/efeitos dos fármacos , Linfócitos B/metabolismo , Antígenos CD4/deficiência , Antígenos CD4/genética , Feminino , Citometria de Fluxo , Centro Germinativo/efeitos dos fármacos , Centro Germinativo/imunologia , Centro Germinativo/metabolismo , Masculino , Camundongos , Camundongos Knockout , Microscopia de Fluorescência , Nanopartículas/química , Ovalbumina/imunologia , PPAR gama/antagonistas & inibidores , PPAR gama/genética , Pioglitazona , Fatores Sexuais , Linfócitos T Auxiliares-Indutores/citologia , Linfócitos T Auxiliares-Indutores/efeitos dos fármacos , Linfócitos T Auxiliares-Indutores/metabolismo , Tiazolidinedionas/farmacologiaRESUMO
T cells express T-cell antigen receptors (TCR) for the recognition of antigen in conjunction with the products of the major histocompatibility complex. They also express two key surface coreceptors, CD4 and CD8, which are involved in the interaction with their ligands. As CD4 is expressed on the early haemopoietic progenitor as well as the early thymic precursor cells, a role for CD4 in haemopoiesis and T-cell development is implicated. Thymocytes undergo a series of differentiation and selection steps to become mature CD4+8- or CD4-8+ (single positive) T cells. Studies of the role of CD4+ T cells in vivo have been based on adoptive transfer of selected or depleted lymphocytes, or in vivo treatment of thymectomized mice with monoclonal antibodies causing depletion of CD4+ T cells. In order to study the role of the CD4 molecule in the development and function of lymphocytes, we have disrupted the CD4 gene in embryonic stem cells by homologous recombination. Germ-line transmission of the mutation produces mutant mouse strains that do not express CD4 on the cell surface. In these mice, the development of CD8+ T cells and myeloid components is unaltered, indicating that expression of CD4 on progenitor cells and CD4+ CD8+ (double positive) thymocytes is not obligatory. Here we report that these mice have markedly decreased helper cell activity for antibody responses, although cytotoxic T-cell activity against viruses is in the normal range. This differential requirement for CD4+ helper T cells is important to our understanding of immune disorders including AIDS, in which CD4+ cells are reduced or absent.