To investigate the membrane structures involved in cellular interactions between thymocytes and macrophages, the relative ability of different murine macrophage populations to spontaneously bind thymocytes was compared. Macrophages derived from the spleen or thymus bound three to four times the number of thymocytes than macrophages from peripheral blood, peritoneum, or bone marrow. This reflect...

Ikaros is the founding member of a small family of C2H2 zinc-finger DNA-binding proteins that carry out critical functions during lymphocyte development. Although interactions between Ikaros and various proteins have been reported, Ikaros-containing complexes have not been purified to determine their composition and identify the predominant interacting partners. In this study, a tandem affinity...

The thymus of adult mice is considered to be the major anatomical site at which immunocompetent T lymphocytes are generated (1). However, the proportion of thymocytes possessing demonstrable immunocompetence is rather low, representing a subpopulation of 10-15 % of cells in the thymus (2). Recently, the phenotypic properties of thymocyte subpopulations have been characterized using monoclonal a...

Recombination of δRec to ψJα will delete the TCR δ gene, which is thought to play an important role in the bifurcation of the TCR αβ versus TCR γδ differentiation lineages. We recently detected a DNA-binding protein in human thymocytes, the so-called PJA-BP, which recognizes the ψJα gene segment and might be one of the factors involved in the regulation of preferential δRec–ψJα rearrangements. ...

The early growth response (Egr)-1 is a zinc finger-containing transcription factor belonging to the immediate-early genes. Its expression in CD4/CD8 double negative (DN) immature thymocytes suggests that Egr-1 expression may be involved in early thymocyte development. In transgenic mice overexpressing Egr-1 in a recombinase-activating gene-deficient background, thymocytes bypassed the block at ...

CD4+CD8+ thymocytes expressing self-reactive T cell antigen receptors (TCR) are deleted in the thymus as a consequence of TCR/self-antigen/major histocompatibility complex interactions. However, the signals that are necessary to initiate clonal deletion have not yet been clarified. Here we demonstrate that TCR engagement does not efficiently induce apoptosis of CD4+CD8+ thymocytes, although it ...

The importance of E2A transcription factors in T cell development has been demonstrated in studies of E2A-deficient mice, which display abnormal T cell development and a high frequency of T cell lymphomas. Because E2A expression is not restricted to the T cell lineage, the primary cause of the T cell phenotype in E2A-deficient mice was not fully determined. To further investigate the role of E2...