E. Marga Janse

Postnatal development of mucosa-associated lymphoid tissues in chickens

SummaryThe postnatal development of chicken mucosa-associated lymphoid tissues of the eyes, lungs, and intestines were investigated with monoclonal antibodies specific for either all leucocytes, B lymphocytes, mononuclear phagocytes, IgM, IgG, or IgA. Attention has been paid to the relation of lymphoid infiltrates with their surrounding mucosae, the segregation into B-cell and T-cell areas, development of germinal centers, and secretory immunoglobulins. Abudant secretory IgM and IgA was detected in the epithelium of the Harderian glands in the orbits, even though they lacked large leucocyte infiltrates with germinal centers. Lymphoid tissues in the mucosae of lungs and intestines developed separate B-cell and T-cell areas. The proventriculus, Meckels diverticulum, and Peyers patches generally contained germinal centers from 12 weeks of age on. Because chickens as young as 2 weeks old had germinal centers in bronchus-associated lymphoid tissue and cecal tonsils, these areas were probably highly stimulated by antigens. Isotype-specific monoclonal antibodies were used to detect IgM-, IgG-, and IgA-bearing follicular cells in the same germinal center.

Monoclonal antibodies as probes for defining cellular subsets in the bone marrow, thymus, bursa of Fabricius, and spleen of the chicken

Using immunohistochemistry, the distribution and characteristics of cells detected by the newly developed monoclonals HIS-CI (B lymphocytes), HIS-C7 (leucocytes), HIS-C12 (IgM), CVI-ChIgM-59.7 (IgM), CVI-ChIgG-47.3 (IgG), and CVI-ChIgA-46.5 (IgA) are described in bone marrow, thymus, bursa of Fabricius, and spleen of chickens of different ages. Furthermore, quantification of cells positive with the described monoclonal antibodies was performed on cytocentrifuge preparations. The specificities of the monoclonal antibodies are discussed.

The monoclonal antibody CVI-CHNL-68.1 recognizes cells of the monocyte-macrophage lineage in chickens

The characteristics of monoclonal antibody CVI-ChNL-68.1, which specifically reacts with a group of chicken non-lymphoid cells, are described. Both tissue distribution shown on cryostat sections using immuno-enzyme histochemistry, and quantitative data obtained on cell suspensions are presented. Functional characteristics of CVI-ChNL-68.1-positive cells, such as antigen uptake and glass adherence, are determined. Results show that CVI-ChNL-68.1 reacts with monocytes, macrophages, and interdigitating cells. Possible relationships between the various non-lymphoid cells are discussed.

Ontogeny and Function of Two Non-Lymphoid Cell Populations in the Chicken Embryo

The purpose of the study was to determine what type of non-lymphoid cells develop in chicken embryos during ontogeny, and whether these cells are functional. To detect these cells, we used monoclonal antibodies specific to two groups of non-lymphoid cells: CVI-ChNL-68.1, specific for mononuclear phagocytes, and CVI-ChNL-68.2, specific for a subpopulation of reticulum cells in spleen, liver and bursa. Monoclonal antibodies HIS-C7, HIS-C1, and HIS-C12, which are specific to leukocytes, B lymphocytes, and IgM respectively, were used to correlate the ontogeny of non-lymphoid cells and lymphoid cells. Mononuclear phagocytes and reticulum cells were detected in the liver, spleen, yolk sac, bursa, gut, and thymus at about the same time as leukocytes, but earlier than B lymphocytes. To determine whether mononuclear phagocytes and reticulum cells in spleen and liver absorb antigen, we injected embryos intravenously with colloidal carbon and the antigen FITC-Ficoll. In addition, acid phosphatase was used as a marker for phagocytic activity. Reticulum cells in the liver and spleen were functional from the first point of detection, whereas mononuclear phagocytes in the liver and spleen started to absorb antigen a few days after their development.

Distribution and function of non-lymphoid cells positive for monoclonal antibody CVI-ChNL-68.2 in healthy chickens and those infected with Marek's disease virus

Immuno-enzyme histochemistry was used to study the staining pattern and tissue distribution of monoclonal antibody CVI-ChNL-68.2 that specifically reacts with a subset of non-lymphoid cells in healthy chickens and those infected with Mareks disease virus (MDV). Functional characteristics of CVI-ChNL-68.2-positive cells, e.g. antigen uptake, are determined. In the liver CVI-ChNL-68.2 recognizes reticulum cells, whereas in the bursa of Fabricius it detects single cells in the interfollicular connective tissue. In the spleen CVI-ChNL-68.2 reacts selectively with the reticulum cells of the ellipsoid. In some MDV-infected chickens the splenic reticulum cells show a different staining and distribution pattern. Furthermore, the proliferative lesions associated with Mareks disease contain many CVI-ChNL-68.2-positive cells. The possible role of CVI-ChNL-68.2-positive cells in disseminating Mareks disease virus is discussed.

Leukocyte subpopulations in kidney and trachea of chickens infected with infectious bronchitis virus.

Using immunohistochemical methods, we studied the nephropathogenicity of the infectious bronchitis virus (IBV)-strain V1648- and the leukocyte phenotypes in the pathological lesions in the kidneys and the trachea formed after inoculation with this virus strain. One-day-old WLA chickens were intravenously inoculated, and after 5, 7 and 11 days their kidneys, trachea and lungs were removed. Monoclonal antibodies were used to detect viral antigen, and lymphoid and non-lymphoid cell populations. In serial sections, the detection of the viral antigen was correlated to the phenotypes of the cells. At days 5 and 7 after inoculation, viral antigen was detected in the epithelium and the interstitium of the kidney tubuli and in the epithelium of the trachea. The infiltrated cells in these tissues were mainly of the T cell phenotype. The cellular immune reaction was correlated with the detection of viral antigen.

MECKEL'S DIVERTICLE: A GUT ASSOCIATED LYMPHOID ORGAN IN CHICKENS

Halfway along the jejunum, closer to the ileum than to the duodenum, a blind ending tube, the Meckel’s diverticle, can be seen in more than 60% of all adult chickens (1). This diverticulum caecum vitelli is the remnant of the omphalomesenteric or vitelline duct that forms the intermediate between the yolk sac and the primitive gut of the embryos. In the first days after hatching, the Meckel’s diverticle is unusually large and filled with yolk, which still functions as food supply for the young chicken (2).

Germinal Centers Develop at Predilicted Sites in the Chicken Spleen

Recently the various compartments of the chicken spleen were investigated for their role during the induction and effector phase of the humoral immune response against T-cell dependent antigens (1). In general, all events in the chicken spleen occurred at similar timepoints and at similar sites as they do in the mammalian spleen. For example, antigen-specific antibody-containing cells were first detected in peri-arteriolar T cell sheaths (PALS) and later in the red pulp (2). The induction of the response was found to occur in the complex of ellipsoid, peri-ellipsoid B lymphocyte sheath (PELS) and surrounding macrophages, which is therefore the functional analogue of the mammalian marginal zone with its sinus, B lymphocytes and non-lymphoid cells (3).Recently the various compartments of the chicken spleen were investigated for their role during the induction and effector phase of the humoral immune response against T-cell dependent antigens (1). In general, all events in the chicken spleen occurred at similar timepoints and at similar sites as they do in the mammalian spleen. For example, antigen-specific antibody-containing cells were first detected in peri-arteriolar T cell sheaths (PALS) and later in the red pulp (2). The induction of the response was found to occur in the complex of ellipsoid, peri-ellipsoid B lymphocyte sheath (PELS) and surrounding macrophages, which is therefore the functional analogue of the mammalian marginal zone with its sinus, B lymphocytes and non-lymphoid cells (3).