RESUMO
Small intestinal cryptopatches (CP) are the major anatomic site for extrathymic differentiation by precursors destined to become intestinal intraepithelial T lymphocytes (IEL). We found that mice deficient in CCR6 exhibited a 2.7-fold increase in the number of alphabeta TCR IEL, but little or no expansion of gammadelta TCR IEL. Among the alphabeta TCR IEL subsets, the CD4- CD8alphaalpha+ and CD4+ CD8alphaalpha+ subsets were preferentially expanded in CCR6 null mice. Because some CD8alphaalpha+ IEL can arise through extrathymic differentiation in CP, we investigated CCR6 expression by T lymphocyte precursors undergoing extrathymic differentiation in intestinal CP. In sections of CP, 50-60% of c-kit+ precursors were CCR6+. CD11c(+) cells concentrated at the periphery of CP did not express CCR6. A subset of c-kit+, Lin- cells in lamina propria suspensions was CCR6+, but CCR6 was absent from c-kit+ precursors in bone marrow. CCR6 was absent from the vast majority of mature IEL. CCR6 is present on lymphocyte precursors in cryptopatches, expressed transiently during extrathymic IEL development, and is required for homeostatic regulation of intestinal IEL.
Assuntos
Mucosa Intestinal/imunologia , Subpopulações de Linfócitos/imunologia , Subpopulações de Linfócitos/metabolismo , Nódulos Linfáticos Agregados/imunologia , Nódulos Linfáticos Agregados/metabolismo , Receptores de Quimiocinas/biossíntese , Células-Tronco/imunologia , Células-Tronco/metabolismo , Animais , Células da Medula Óssea/citologia , Células da Medula Óssea/imunologia , Células da Medula Óssea/metabolismo , Antígenos CD8/biossíntese , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Divisão Celular/genética , Divisão Celular/imunologia , Linhagem da Célula/genética , Linhagem da Célula/imunologia , Dimerização , Proteínas de Fluorescência Verde , Mucosa Intestinal/citologia , Mucosa Intestinal/metabolismo , Intestino Delgado/citologia , Intestino Delgado/imunologia , Intestino Delgado/metabolismo , Proteínas Luminescentes/biossíntese , Proteínas Luminescentes/genética , Subpopulações de Linfócitos/citologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Nódulos Linfáticos Agregados/citologia , Proteínas Proto-Oncogênicas c-kit/biossíntese , Receptores de Antígenos de Linfócitos T alfa-beta/biossíntese , Receptores CCR6 , Receptores de Quimiocinas/deficiência , Receptores de Quimiocinas/genética , Células-Tronco/citologia , Subpopulações de Linfócitos T/citologia , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Antígenos Thy-1/biossíntese , Regulação para Cima/genética , Regulação para Cima/imunologiaRESUMO
The homing properties of subsets of lymphocytes and dendritic cells (DC) are regulated in part by the profile of chemokine receptors expressed. To determine how CCR6 influences cell trafficking, a mutant allele of the mouse CCR6 gene was produced that includes an enhanced green fluorescent protein (EGFP) reporter under the control of the CCR6 promoter. In mice heterozygous for the EGFP/CCR6 knock-in, CCR6 expression was detected on all mature B cells, subpopulations of splenic CD4(+) and CD8(+) T cells, and on some CD11c(+) DC. Most CD11b(+) myeloid DC expressed CCR6, but CD8alpha(+) lymphoid DC were negative for CCR6. Among myeloid DC, the CD4(+) subset was uniformly positive for CCR6 expression and the CD4(-) subset was mostly CCR6 positive. Epidermal Langerhans cells (LC) also expressed CCR6, but at lower levels than splenic myeloid DC. Culture of bone marrow precursors from the knock-in mice with GM-CSF for 4 to 6 days led to the appearance of a subset of CD11c(+) DC expressing CCR6. The differences in CCR6 expression among the major DC subsets indicate that CCR6 and its chemokine ligand MIP-3alpha participate in determining the positioning of DC subsets in epithelial and lymphoid tissues.