In situ localization of T cell receptor beta chain in the murine thymus: changes in the intrathymic distribution of thymocytes expressing beta chain during fetal development

Involvement of E-cadherin in thymus organogenesis and thymocyte maturation

We examined the role of E-cadherin expressed by thymic epithelial cells and immature thymocytes in thymus organogenesis and thymocyte development. ECCD-1 MAb, which blocks homotypic E-cadherin interactions, inhibited epithelial organization and thymocyte development in reaggregate fetal thymic organ cultures. It also interfered with the differentiation of fetal liver cells or fetal thymocytes within deoxyguanosine-treated thymic lobes, but did not affect thymocyte development in intact cultured fetal thymic lobes. In contrast, antibodies that selectively inhibit interactions between E-cadherin and alpha(E)beta7 integrins did not perturb thymic epithelial organization or thymocyte development, suggesting that homotypic E-cadherin interactions play an important role in thymus development and function.

Analysis of mature guinea pig T cells with a monoclonal antibody directed against a framework determinant of the T-cell receptor for antigen

Rats were immunized with guinea pig T lymphocytes and the spleen cells were fused with cells of a mouse myeloma line. The resulting hybrids were screened for the production of antibodies selectively reacting with guinea pig T cells. The monoclonal antibody (MoAb) H159 was analysed in detail because it bound to T lymphocytes, but not to B lymphocytes or macrophages. Cellular ELISA, cytofluorometry and immunohistology revealed that the antigen detected by H159 is selectively expressed on the majority of peripheral mature T lymphocytes (about 95%). In contrast, it stained only a minor population of thymocytes in FACS analysis. H159 precipitated from NP40 lysate of T cells a protein with a molecular weight of about 90 kDa when separated under non-reducing conditions in SDS-PAGE. Under reducing conditions bands with molecular weights of about 50 kDa were found. After binding to anti-rat Ig coated beads, the MoAb H159 had a mitogenic effect for guinea pig T lymphocytes whereas soluble MoAb H159 in the presence or absence of macrophages was not mitogenic. The cellular expression and molecular characteristics of the H159 antigen together with the mitogenic activity of the antibody for T cells indicate that the MoAb H159 recognizes the guinea pig T-cell receptor for antigen via a constant region determinant.

Characterization of murine thymocyte subpopulations reacting with Dolichos bifloris agglutinin

Reactivity of murine thymocytes with the Dolichos bifloris agglutinin (DBA) was examined using flow cytometry. This agglutinin, which has nominal specificity for alpha-linked N-acetyl-D-galactosamine residues, labels 1-4% of unfractionated BALB/c thymocytes. Among thymocyte subpopulations identified on the basis of CD4/CD8 labeling, DBA bound to a substantial percentage of the CD4-8- thymocyte subpopulation. In addition, small populations of thymocytes expressing CD4 and/or CD8 were also labeled with DBA, but with less intensity then seen on many CD4-8- cells. Within the CD4-8- thymocyte population, labeling with DBA was positively correlated with reactivity with J11d antibody, the expression of IL-2 receptor and high levels of the homing receptor molecule, MEL-14. Reactivity with DBA was negatively correlated with the expression of Lyt-1, V beta 8 TCR determinants, and CD3.