TL;DR: Although measles-determined aggregative destruction of thymocytes can cause rapid loss of cortex, the final histological picture of the latter need not necessarily have been preceded by the same type of measles-dependent thymocyte destruction.
Abstract: The histological changes in the thymus and other lymphoid tissues in cases of severe measles resulting in death during the acute phase or at sometime afterwards (from a presumably unrelated cause) have been surveyed and compared with cases of similar age and duration of illnesses other than measles which were admitted to the same infectious diseases hospital. Severe changes of aggregation and formation of large syncytia of thymocytes which progressed to cytoplasmic and nuclear destruction were observed early in the disease (at 4 days). These `giant-cells' failed to show either nuclear or cytoplasmic inclusion bodies. Such cases when seen at a later stage had total loss of thymic cortex. After measles the cortex of the thymus can be absent for at least 2 months. Thus no cortex was discernible in cases of post-measles death at 28 and 64 days; recovery of cortex was seen at 91 and 122 days.
Other cases of severe systemic disease entering the same hospital also showed loss of thymic cortex from 6 days of illness. Thus, although measles-determined aggregative destruction of thymocytes can cause rapid loss of cortex, the final histological picture of the latter need not necessarily have been preceded by the same type of measles-dependent thymocyte destruction.
Although thymocyte aggregation and secondary depletion were the most obvious histological result, a careful quantitation of the medulla and of HassalFs corpuscles showed a small decrease in both tissues in the acute phase. Cases recovering from measles showed a small decrease in the number of Hassall's corpuscles. Measles-specific changes were not found in lymphoid tissues other than the thymus of these cases.
TL;DR: Induction of rat thymocyte aggregation by anti‐leukosialin antibodies requires bivalent cross‐linking and maximal aggregation is dependent on energy and an, intact cytoskeleton.
Abstract: Leukosialin (CD43) is a major glycoprotein of T lymphocytes which has an extracellular domain of 45 nm in length that is heavily O-glycosylated. Monoclonal antibodies (mAb) to the extracellular domain of human leukosialin induce aggregation of T lymphocytes, monocytes and some cell lines that express leukosialin. The aggregation was reported in one case to be inducible by Fab fragments. In the present study, nine mAb specific for rat leukosialin were tested as inducers of thymocyte aggregation and all were effective. The level of aggregation was reduced by metabolic and cytoskeletal inhibitors, by removal of divalent cations and by reducing the temperature from 37 degrees C to 4 degrees C. The aggregation produced by mAb specific for certain epitopes was less sensitive to these inhibitors than aggregation induced by mAb to other epitopes. To examine the requirement for cross-linking, Fab fragments of four of the antibodies were tested and found to be inactive except for those derived from the OX75 mAb. However, OX75 Fab showed a tendency to dimerize, and monomeric OX75 Fab obtained directly after gel filtration was unable to induce aggregation. Thus induction of rat thymocyte aggregation by anti-leukosialin antibodies requires bivalent cross-linking and maximal aggregation is dependent on energy and an intact cytoskeleton. Mechanisms of antibody-induced aggregation are considered and it is proposed that in the case of leukosialin the antibodies may cross-link cells to overcome inherent repulsion between them and that subsequently other adhesion molecules complete the clustering process.
TL;DR: Thy-3 is a T lineage-specific glycoprotein associated to Thy-1 in membrane microdomains and might contribute to the function of Thy- 1 in T-cell differentiation.
TL;DR: A murine mAb, 7D3, was produced by fusion of spleen cells obtained from mice immunized with a rat thymic epithelial cell line, Tu-D3 and NS/1 myeloma cells and inhibited the thymocyte binding to thymi epithelial cells.
Abstract: A murine mAb, 7D3, was produced by fusion of spleen cells obtained from mice immunized with a rat thymic epithelial cell line, Tu-D3 and NS/1 myeloma cells 7D3 antibody reacted with approximately 95% thymocytes, 17% spleen cells, less than 9% of mesenteric lymph node cells and 32% of bone marrow cells of rat origin 7D3 also reacted with two rat thymic epithelial cell lines but not with a rat fibroblastic cell line Immunochemical analysis demonstrated that 7D3 antibody recognized a single polypeptide with molecular weight of 80,000 in FTE cells and 80,000 to 96,000 in thymocytes 7D3 antibody strongly inhibited the thymocyte binding to thymic epithelial cells In addition, 7D3 antibody inhibited TPA-induced thymocyte aggregation 7D3 negative rat thymic lymphoma cells bound to 7D3 positive thymic epithelial cells and this binding was inhibited by 7D3 antibody, indicating that a part of thymocyte-thymic epithelial cell binding was mediated by the interaction of 7D3 Ag and undefined ligand to 7D3