Antibody class switching is mediated by a DNA recombination event that replaces the Cμ gene with one of the other heavy (H) chain constant region (CH) genes located 3
Interleukin 4 (IL-4) is a cytokine that is involved in the differentiation of B and T lymphocytes. In this report, we describe the identification of a novel gene, N.52, which was cloned from the murine pre-B cell line R8205 grown in the presence of IL-4 for 48 hr. Although N.52 expression is detectable at low levels in unstimulated R8205 cells, the level of N.52 dramatically...
Many, if not all, of the different phases of intrabursal B-cell maturation are controlled by the stromal components. We have used an extensive panel of mAb to provide a detailed phenotypic profile of these cells. Antigenic specificities were defined for the entire surface epithelium, interfollicular surface epithelium, follicle-associated epithelium, basement membrane, basement...
Immunoglobulin genes are generated during differentiation of B lymphocytes by joining gene segments. A mouse pre-B cell contains a functional immunoglobulin heavy-chain gene, but no light-chain gene. Although there is only one heavy-chain locus, there are two lightchain loci: κ and λ.It has been reported that κ loci in the germ-line configuration are never (in man) or very rarely...
It is well established that the majority of murine fetal thymocytes (day 15 of gestation) express receptors for interleukin 2 (IL-2), but the functional significance of these IL-2 receptors (IL-2Rs) is not clear. In situ hybridization data show a developmentally regulated expression of IL-2 and IL-2R mRNA. IL-2 binding studies were performed on fetal thymocytes and the results...
Three distinct T-cell precursors: bone marrow cells that express low levels of the Thy-1 antigen but no lineage markers (Thy-1-lo/BM); CD4-, CD8-, and CD3- thymocytes that express low levels of the Thy-1 antigen (Thy-1-lo/Thym); and CD4-, CD8-, and CD3- thymocytes that express high levels of the Thy-1 antigen and the IL-2 R α chain (Thy-1
We obtained eight different cell lines in the long-term bone marrow culture system that showed a germ-line configuration of the joining (J) region segments of the Ig heavy-chain (IgH) genes. Their surface markers were CD45R
This work was undertaken to investigate whether or not antigen processing and presentation are important in channel catfish in vitro secondary immune responses elicited with structurally defined proteins, namely, pigeon heart cytochrome C (pCytC), hen egg lysozyme, and horse myoglobin. The use of in vitro antigen-pulsed and fixed B cells or monocytes as antigen presenting cells...
Five stromal-cell-dependent lymphocyte clones are described that correspond to late pre-B or early B-cell stages of differentiation.They are useful for determining the molecular requirements for pre-B replication, for studying the stromal cells that supply those factors, and for delineating the final sequence of differentiation events as newly formed lymphocytes prepare to exit...
Allogeneic immunocompetent T cells injected into chicken embryos induce a graft-versushost reaction (GVHR) whose most prominent manifestation is splenic hyperplasia. The highly inbred CC and CB strains of chickens used here are, respectively, homozygous for the B4 or B12 MHC haplotypes. By means of a panel of immunological reagents, including alloantisera and monoclonal...
Precursors of B cells capable of responding to a T-independent form of phosphorylcholine (PC) in splenic focus assays were detected in the spleens of neonatal mice as early as 4 days after birth. The earliest anti-PC B cells were T15-. T15
In inbred strains of mice, antiphosphorylcholine (PC) and anti-α1,3 dextran (DEX). antibodies are structurally distinct from each other and have been shown to exhibit noncrossreactive antigen binding and idiotypic specificities. However, the prototype anti-PC and anti-DEX antibodies, TEPC15 and J558, respectively, were shown to be connected via a common autoantiidiotypic...
Thymic rosettes (ROS), structures consisting of thymic lymphoid cells attached to a central stromal cell, were isolated from mouse thymus by collagenase digestion and unit-gravity elutriation. The ROS were then separated into those where the stromal cells were either macrophage-like (M-ROS) or dendritic cell-like (D-ROS), on the basis of the differences in adherence properties or...
N-methyl-N-nitrosourea induces murine CD4-8
In previous experiments, we have demonstrated that limb buds engrafted during embryonic life at E4, between MHC-mismatched chick embryos, are not only tolerated after birth, but induce in the recipient a state of split tolerance toward cells expressing the donor MHC haplotype: donor's skin grafts are permanently tolerated while a proliferative response of host's T cells is...
Stromal macrophages in lymphohemopoietic tissues express novel macrophagerestricted plasma membrane receptors involved in nonphagocytic interactions with other hemopoietic cells. One such receptor with lectinlike specificity for sialylated glycoconjugates on sheep erythrocytes and murine hemopoietic cells has been characterized immunochemically and termed sialoadhesin. We have...
The development of monoclonal antibodies (mAb) reactive with the thymic microenvironment has identified distinct subpopulations within the stromal component, but the function of these subregions in intrathymic T-cell differentiation remains essentially an enigma. In this study, we have used such a panel of mAb to examine the chicken thymus during ontogenic development to gain...
Mouse embryonic stem (ES) cells can differentiate in culture to late stages of many cell lineages. have found culture conditions that are favorable for development in vitro of ES cells into hematopoietic cells at a stage equivalent to day 11-14 of fetal liver development. describe here: (1) the growth conditions necessary for maintenance of ES cells in an undifferentiated state...
Phenotypic profiles of the thymic stromal components provide an excellent approach to elucidating the nature of the microenvironment of this organ. To address this issue in chickens, we have produced an extensive panel of 18 mAb to the thymic stroma. These mAb have been extensively characterized with respect to their phenotypic specificities and reveal that the stromal cells are...
To investigate the role of thymic myoid cells in the pathogenesis of myasthenia gravis (MG), mRNA of nonneoplastic thymuses from eight MG patients was analyzed by dot blot hybridization for the occurrence of acetylcholine receptor (AChR) subunit transcripts, using the five AChR-subunit cDNAs (alpha, beta, gamma, delta, and epsilon) as probes. Attention was particularly paid to...
The coincidence of autoantibodies against the acetylcholine receptor (AChR) and muscle striational antigens (SA) is a characteristic finding in thymoma-associated myasthenia gravis (MG), but their origins are still unresolved. Some common muscle antigens that were shown to be targets of anti-SA autoantibodies in thymoma-associated MG have also been detected in normal or...
Introduction of a transgenic αß TCR (Vα2, Vß8.1) specific for lymphocytic choriomeningitis virus (LCMV), in the context of H-2Db into the genome of C57BL/6 mice, has many effects on the development and selection of T cells in both the thymus and the periphery. These mice produce increased numbers of CD4–8
T-cell receptor (TCR) ß-chain usage and expression of the CD3, CD4, and CD8 differentiation antigens were analyzed in 14 spontaneous AKR lymphomas. Lymphoma cells massively infiltrated and/or proliferated in the organs analyzed (thymus, spleen, and mesenteric lymph nodes), giving rise to a loss of organ structure. One lymphoma occurred only in the thymus, and failed to express...
To investigate the age-dependent mechanism of susceptibility for chicken anemia virus (CAV) infection, we inoculated embryos and chickens of ages between day 9 of embryonic development and day 28 after hatching with CAV. Chicken embryos inoculated at days 9 and 11 of development showed no CAV-infected cells in the thymus, nor in other lymphoid organs. Many CAV-infected cells were...