E. W. A. Kamperdijk

An improved and rapid method for the isolation of rat lymph node or spleen T lymphocytes for T cell proliferation assays

To detect and compare the capacity of antigen presenting cells to present antigen in a T cell proliferation assay, it is necessary to obtain a pure population of antigen-primed T cells that gives low background proliferative responses. Therefore in this paper we present a newly developed isolation method of antigen-primed T lymphocytes from rat spleen or lymph nodes. This method uses a nylon wool column to deplete most of the adherent cells and B cells, followed by an indirect elimination method with magnetic beads to remove contaminating Ia-positive cells. We compared this method with two commonly used isolation methods, namely a 1.5 h adherence step, followed by a nylon wool column and a Sephadex G-10 column and a 1.5 h adherence step followed by a passage through two consecutive columns of Sephadex G-10. The best T cell enrichment (98% OX-19/52-positive cells) was achieved with the newly developed method, in which the contamination of Ia-positive cells, predominantly B cells and dendritic cells (DC), was diminished to less than 2%. The background response of this population was low and differed significantly with the common methods. Antigen-specific T cell responses induced by splenic DC, expressed as stimulation index, gave very specific responses and showed a steep rise with increasing DC concentrations compared to the common methods. Therefore we conclude that we developed an improved, rapid and reproducible method for the isolation of rat spleen or lymph node T lymphocytes suitable for T cell proliferation assays.

Rat Thymic Dendritic Cells

The aim of this study was to compare rat thymic dendritic cells in situ (i. e. interdigitating cells, IDC) with isolated dendritic cells (1) using enzyme cytochemical, immunocytochemical and electron-microscopical methods. Moreover the phenotypical and morphological changes of these isolated dendritic cells were studied after culture. To get more information about the influence of size (volume) and/or micro-environment on antigen presentation, we also compared the capacity to present GT to primed T cells by freshly isolated dendritic cells from thymus, spleen and peritoneal cavity.

Three Monoclonal Antibodies to Antigen Presenting Cells in the Rat with Differential Influence on Cellular Interactions

A physical interaction between antigen presenting cells (APC) and T cells is essential for evoking an immune response1. It has been proposed that T cells first bind to APC by an antigen-independent mechanism. Antigen specific lymphocytes are then selected and activated within the APC-T cell cluster resulting in T cell proliferation2. In the first stage several accessory molecules, like LFA-1, ICAM-1, CD2, and LFA-3, are involved in the antigen-independent interaction1,2,3. Thereafter the antigen-dependent interaction, mediated by the T cell receptor (TCR), CD3, CD4, and the MHC Class II molecule, becomes more important and induces cytokine production triggering T cell proliferation1,3,4,5. In the third stage, which can occur in the absence of APC, IL-2 alone mediates proliferation of the responsive T cells.

Macrophages in Different Compartments of the Non-neoplastic Lymph Node

Lymph nodes are encapsulated, commonly kidney-shaped, organs which filter tissue fluid supplied by afferent lymph vessels. In most species these vessels pierce the capsule on the convex surface and open into the subcapsular sinus, which is ultimately integrated with the medullary sinuses in the concavity of the hilus of the organ. The lymph is filtered in the fine meshes of the reticuloendothelial tissue (stroma) which supports the sinuses and the compact lymphatic tissue of the node. After filtration the lymph leaves at the hilus via the efferent lymphatic vessels, which usually follow the route of the larger veins and may either join a large collecting lymphatic duct or link with another lymph node as afferent vessels. Finally all lymph is collected in large lymphatic ducts which join the bloodstream at the base of the neck in the subclavian veins. All lymph vessels possess small valves to force the lymph stream in one direction.

Normal Anatomy, Histology, Immunohistology, and Ultrastructure, Lymph Node, Rat

The lymph nodes of the rat are small, round, or kidney–shaped organs with a length of 3–5 mm which can be distinguished from the surrounding fat by their pearly gloss. They occur dispersed throughout the body, always connected with lymph vessels. Particularly in the axillar, inguinal, and cervical regions, along the larger arteries, and within the mesenterium, groups of nodes can be found (Fig. 124; Tilney 1971). The nodes are surrounded by a fibrous capsule from which trabeculae emerge. At the convex side thin afferent lymph vessels are recognizable, at the concave side (the hilus) small arteries and nerves supply the node, and the efferent lymph vessels and veins leave the node. The lymph vessels possess small valves to force the lymph stream in one direction. Though there are small variations between the different lymph nodes, in general the architecture is about the same. On cross section the cortex with small white nodules can be discriminated from the centrally located medulla. As an exception to the regular nodes, the renal nodes are reddish, due to the large numbers of red blood cells within the medullary region; these nodes are designated as hemolymph nodes (Andreasen and Gottlieb 1946). Like all other lymph nodes these nodes are interposed in the lymphatic stream and thus possess normal afferent and efferent lymph vessels (Kazeem et al. 1982).

The Ontogenetic Development of the Follicular Dendritic Cell in Rat Spleen

Secondary follicles of lymphoid organs contain a highly specialized non-lymphoid cell type, the so-called follicular dendritic cells (FDC). FDC are cells with extraordinary long slender cell processes, which form an intricate labyrinth of invaginations11,12 in which antigen-antibody complexes can be trapped and retained for several weeks2. This trapping is believed to play a role in the induction of immunological memory17 or as feedback mechanisms regulating the immune response24.