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Biomedical subjects

M Papiernik

Publications and source records attributed to M Papiernik.

At least 73 records · Page 4Linked to original sources
PubMed1982

Postnatal development of T cells. III. Thymus independency of T-cell-dependent antigen response in the neonatal spleen.

Neonatal spleens were grafted under the kidney capsule of adult syngeneic mice which were either normal, thymectomized, splenectomized or both thymectomized and splenectomized. After 14 days in situ, grafts were exised and the total cell number, the number of Thy-1 and Ig-positive cells, the plaque-forming cell (PFC) response after in vivo immunization with SRBC, and the suppressive activity in vitro on immune cells were determined. The expansion of the T-cell-precursor pool was not dependent upon the presence of the host thymus, nor was the antibody response, which was of neonatal type, i.e. with low PFC response and high suppressive activity. Host splenectomy enhances dramatically the proliferation of neonatal spleen graft cells and their ability to respond to SRBC. This enhancement is essentially due to a host cellular contribution, and is not observed when the graft is an adult spleen fragment. These results suggest that the spleen itself could have a regulatory role in postnatal lymphoid development.

Aging↗
PubMed1982

Impairment of T lymphocyte functions in mice with motor end-plate disease.

The present paper reports complex immunological anomalies associated with motor end-plate disease (Med) in mice. Motor end-plate disease is a severe neuromuscular disorder which leads to death (around the 25th of life) in the Medj/Medj mutant, while the heterozygotes quickly recover from mild manifestations. Medj/Medj and Medj/ + mice share some of the immunological aberrations: reduced PFC response to SRBC in 14-16 day old mice, with reduced suppressor cell function and precocious maturation of the cytotoxic response to allogeneic cells in 21-23 day old mice. The diminished PFC response is corrected in adult Medj/ + mice but persists in the small group of Medj/Medj which escape death and which were studied between the 6th and 16th week of life. In addition, the thymus and spleen of Medj/Medj mice are greatly reduced in size, a symptom which appears with the onset of the clinical disease. Also, a reduction in the NK activity in the small group of older, surviving mice was noted. T and B lymphocyte proportions and the proliferative responses to T cell mitogens were not impaired in 14-16 day old mice. The role of these abnormalities in the pathogenesis of the disease is not known. Since some of these anomalies are shared by Medj/Medj and Medj/ +, the latter of which present no or mild and transient neurological manifestations, there is no clear link between the immunological and neuromuscular disorders.

Animals↗
PubMed1981

Cellular and molecular signals in T cell differentiation.

The thymic epithelium exerts its differentiative effects through several mechanisms, involving direct contact with stem cells as well as secretion of various thymic hormones. Indirect and direct evidence suggests that the thymus produces chemotactic factors for the stem cells that colonize the thymus anlage. The epithelium also produces several maturational factors which act upon stem cells that have undergone primary differentiation by contact with thymic epithelium. The chemical characteristics of these hormones and their mode of action at the cellular level (high affinity receptors, metabolic effects, target cells) are partly known. Their relationship with T cell factors such as Interleukin-2--produced in the periphery and endowed with strong differentiative capacity--is intriguing, the more so because thymic hormones not only act within the thymus but also affect peripheral T cells after they have emigrated from the thymus.

Animals↗
PubMed1981

Prostaglandin secretion by human thymic epithelium: in vitro effects of steroids.

Increasing evidence suggests a role for prostaglandins in the immune response. As steroids have been shown recently to modulate prostaglandin secretion, we have studied the secretion of prostaglandin and the effect of various steroids in culture of human thymus epithelial cells. Using reverse phase high pressure liquid chromatography and radioimmunoassays, we have shown that these cells produce substantial amounts of PGE2 and PGF2 alpha and that this secretion is modulated by steroid hormones. Prostaglandin could represent one of the factors of the thymic environment which respond to steroid hormones.

Cells, Cultured↗
PubMed1981

Impairment of antibody response and of suppressor cell ontogenesis by early injection of hydrocortisone.

The appearance of antibody responsiveness against sheep red blood cells (SRBC) was studied in young mice treated with hydrocortisone hemisuccinate (HHC) either during gestation or around delivery (last 5 days of gestation or day of birth). The plaque forming cell (PFC) response was normal at 2 weeks and depressed at 4 weeks in animals treated during the last 10 days of pregnancy. Conversely, when HHC was only given around delivery, PFC response was depressed at 2 weeks and normal at 4 weeks. The presence of suppressor cells in unimmunized 1--2-week-old spleen cells was evaluated by co-culturing them with adult spleen cells from mice immunized against SRBC. Suppressive activity was found at high level at 8 days, and had already declined at 15 days in non-treated mice. Spleen cells from mice treated with HHC around delivery showed reduced suppressive activity at 8 days but this activity was very high on the 15th day, greater than in normal mice. Such highly suppressive activity correlated with a high level of Lyt-123 T cells. These data on suppressor cells indicate that the paradoxical effect of HHC in mice treated during gestation or around birth is probably explained by the differential effect of HHC on the kinetics of suppressor cells in ontogeny.

Animals↗
PubMed1981

Thymic involution in pregnant mice. II. Functional aspects of the remaining thymocytes.

Non-specific immunological modifications in mice during syngeneic gestation can be demonstrated. A dramatic transient thymic involution results from a significant reduction in the subpopulations of the thymic cortex with the remaining thymocytes being mainly medullary in nature. Response to PHA and Con A is greatly reduced in this pool which can normally be strongly stimulated. No suppressor cells or alteration in thymic epithelial function could be demonstrated. The unexpected low responsiveness of the remaining thymocytes was reversible after in vitro neuraminidase treatment. Meanwhile, MRL of thymocytes to allogeneic cell during syngenic gestation was not impaired.

Animals↗
PubMed1981

Thymic involution in pregnant mice. I. Characterization of the remaining thymocyte subpopulations.

Pregnancy-induced thymic atrophy was studied in mice during the course of syngeneic gestation and the post-partum period. Cortical thymocytes were greatly reduced in number as shown by the binding of fluorescein-labelled PNA. The pool of steroid-resistant (SR) medullary thymocytes appeared unchanged in pregnant mice when studied by means of a specific heteroantiserum (SRCA). Therefore, in pregnant mice, these two surface markers demonstrated that thymic atrophy was linked to steroid-sensitive (SS) cortical cell reduction. The presumed hydrocortisone resistance of the mother's remaining thymocytes is not related to a difference in the number of steroid receptors as determined by 3H-dexamethasone binding.

Animals↗
PubMed1981

Thymic reticulum in mice. I. Cellular ultrastructure in vitro and functional role.

Qualitative and quantitative electron microscopic studies of thymic and splenic stroma cultured in vitro are described. Under our technical conditions, 60% of thymic stromal cells in vitro are endodermic epithelial cells, while the remaining cells are mesenchymal reticular cells and macrophages. These last two types of cells, together with fibroblasts are the constituents of splenic stroma. In seven experiments, the coculturing of thymic lymphocytes with thymic monolayers led to an enhancement of the Con A response, while coculturing with splenic monolayers did not. These results underline the specific role of thymic epithelial cells in the process of T-cell maturation. Bone marrow cells and spleen cells from B mice are not modified by coculture with thymic epithelium. Reinjection of B mice with bone marrow cells pre-incubated on thymic monolayers did not lead to any reconstitution of T-cell function when tested 1 mth later. These results are interpreted as the inability of thymic stroma from adult mice alone to induce the maturation of pre-T cells.

Animals↗
PubMed1980

[Effect of steroid hormones on the secretion of prostaglandins by human thymic epithelial cells in culture].

Increasing evidence suggests a role of prostaglandins in the immune response. As steroids have been shown recently to modulate prostaglandin secretion, we have studied the secretion of prostaglandin and the effect of various steroids in cultures of human thymus epithelial cells. Using thin layer chromatography and radioimmunoassays, we have shown that these cells produce substantial amounts of PGE2 and PGF2 alpha and that this secretion is modulated by steroid hormones. We therefore suggest that prostaglandin could represent one of the factors of the thymic environment involved in lymphocyte maturation, which respond to steroid hormones.

Cells, Cultured↗
PubMed1977

Thymocyte subpopulations in young and adult mice. I. Separation by density gradient and steroid treatment.

Thymocyte subpopulations obtained after centrifugation on Ficoll density gradients have been studied in young and 6-week-old mice. Whereas the totality of the thymocytes appeared theta-positive, gradient fractionation showed the existence of a subpopulation of immunoglobulin and theta-negative lymphocytes among the lightest cells. Similar separation was obtained in both age groups in terms of the distribution of such theta-negative cells as well as of phytomitogen responses. However, cell pools with characteristics of cortical cells were less well represented in 2 to 10-day-old mice than in adult mice, indicating that post-natal thymic development is essentially associated with the appearance of cortical cells. The gradient did not however, provide a clear separation assessed on other parameters such as theta antigen, concanavalin A and phytohemagglutinin responses and steroid sensitivity. Cellular heterogeneity for a given cell density is discussed in relation to the hypothesis of two separate maturation pathways of thymocytes.

Age Factors↗
PubMed1977

Thymocyte subpopulations in young and adult mice. II. Study of steroid-resistant populations by means of a specific heteroantiserum.

Mouse steroid-resistant (Sr) cells of the thymus have been studied by means of a specific heteroantiserum. This antiserum was obtained in the rabbit after immunization with Sr thymocytes followed by absorption with high density cells isolated on a Ficoll density gradient shown to include a majority of steroid-sensitive (Ss) cells. Antigens defined by this antiserum were found on Sr thymocytes and on a significant portion of spleen and lymph node cells, but not on Ss cortical thymocytes. Cells sensitive to this antiserum appear early in the thymus (by day 15 of gestation) at the same time as Ss cells. These results suggest (a) the existence of an autonomous Sr cell line, with its own antigenic markers appearing early in ontogeny (at the same time as Ss cells), and showing wide heterogeneity in density, possibly linked to variable degrees in maturation, and (b) the medullary origin or some peripheral lymphocytes in lymph node and spleen cells that share antigenic markers with Sr thymocytes.

Age Factors↗