No abstract

Transgenic mice expressing simian virus 40 T antigen under control of the insulin gene regulatory region vary in their response to this protein. Each lineage is characteristically either tolerant to T antigen, or not, in which case autoantibodies arise with high frequency, and lymphocytes infiltrate and disrupt the pancreatic islets. Both non-tolerance and the autoimmune response appear to result from delayed onset of T antigen expression during beta cell development.

Shear stress alters endothelial adhesiveness for monocytes; at early time points, this effect is largely due to flow-stimulated release of NO and, to a lesser extent, prostacyclin. This effect of flow occurs within 30 minutes and is probably due to alterations in the signal transduction or activation state (rather than the expression) of endothelial adhesion molecules.

Transmission of the bovine papillomavirus-1 (BPV-1) genome through the mouse germ line results in the heritable formation of fibropapillomas of the skin, a tissue-specific phenotype analogous to that observed in natural BPV-1 infection of cattle. Oncogenesis is slow, with tumours first arising at 8-9 months of age, usually in areas prone to wounding. Extrachromosomal BPV-1 DNA is detected in all tumours, whereas normal tissues show only integrated DNA.

Lymphocytes from the synovial fluid of patients with rheumatoid arthritis were examined for the expression of granzyme A and perforin. Previous studies have demonstrated that the expression of these proteins, which are implicated as mediators of cytotoxicity, can be used to identify putative cytolytic lymphocytes in vivo. Twenty-two synovial fluid samples were analyzed by in situ hybridization and immunohistochemistry. In six patients receiving low doses of immunosuppressant, a population of granzyme A-and perforin-expressing lymphocytes could be identified. In contrast, lymphocytes from patients who were receiving high doses of immunosuppressant did not contain any granzyme A-or perforin-expressing lymphocytes. Synovial fluid lymphocytes from patients with osteoarthritis did not express either marker.