O papel modulador do gene AIRE - capes

in the V(D)J recombination of T cell receptor gene segments (TRA, TRB, TRGand TRD) [13].The early fetal thymus has homogeneous cell populations composed oflymphoid progenitors derived from the bone marrow, which is formed by doublenegative(DN1), CD44 high CD25 + (DN2), CD44 low CD25 + (DN3), and CD44 lowCD25 - (DN4) thymocytes. During DN to CD4 + CD8 + double-positive (DP)transition, thymocytes relocate to the thymic cortical region, where most do notrecognize the available MHC molecules expressed by thymic stromal cells anddie as a result.The remaining DP thymocytes undergo negative selection occurring both inthe cortex and in medulla, leading to the deletion of autoreactive clones andfavoring MHC-restricted CD4 and CD8 single-positive T cells (CD4 + SP andCD8 + SP), which finally gain the periphery [14,15].In contrast, the newborn and adult thymus is the arrival place of newcolonizing precursors, which contribute to the formation of heterogeneous cellpopulations, including macrophages and dendritic cells [16].Studies on temporal V(D)J recombination of TRA and TRB genes [17,18] anddifferential expression of immune system-related genes, such as interleukinsand the major histocompatibility complex (MHC) [19] during thymus ontogeny,showed that the genetic background of different inbred mouse strains plays animportant role in the modulation of the emergence of T cell maturation.The cDNA microarray, as a high-throughput functional genomic technology,provides comparative analysis between the different phases of thymusontogeny, yielding quantitative expression data of hundreds or thousands ofgenes in a single experiment. Research on gene expression during thymus238