Morphology and formation of symplasts in cell cultures infected with measles virus

The morphology and formation of giant cells were studied in diploid r-68 and MRC-5 cells in comparison with Vero cells at different times after inoculation with measles Leningrad-16 virus by electron and light microscopy and morphometry. The virions were released mainly from mononuclear cells and small syncytia. The nuclei were positioned centrally in the syncytia formed by diploid cells and at the periphery in Vero cell culture. The examined cultures were similar in terms of virus titers but differed by morphology, size and number of syncytia per unit of surface and time course of their formation. In comparison with Vero cells, in diploid r-68 and MRC-5 cells the maximal number involved in giant cells was 5 and 3.5 times lesser and the number of syncytia per surface unit 20 and 13 times lesser, respectively. Human r-68 diploid cell culture was characterized by the least number and size of syncytia over the entire course of experiment and longest life of the monolayer.     

Rolling in P-selectin-deficient mice is reduced but not eliminated in the dorsal skin

P-selectin-mediated rolling is believed to be important in the recruitment of leukocytes to tissue after ischemia-reperfusion injury. The dorsal skin chamber was used to examine differences in the rolling and stable adhesion of circulating leukocytes in subcutaneous (SC) vessels of P-selectin-deficient and age-matched wild-type mice, both under basal conditions and after ischemia-reperfusion. Rolling in the postcapillary venules in SC tissue of P-selectin-deficient mice was significantly lower than that in wild-type mice under the basal conditions and post-ischemia-reperfusion (P < .05), but was not eliminated by the deletion of the P-selectin gene. No significant difference between P-selectin-deficient and wild-type mice in shear rate or leukocyte-endothelial adhesion was observed up to 24 hours after ischemia-reperfusion. These results show that P-selectin-mediated rolling is not a prerequisite for ischemia-reperfusion-induced leukocyte-endothelial adhesion in the skin.     

Immune reconstitution following bone marrow transplantation: comparison of recipients of T-cell depleted marrow with recipients of conventional marrow grafts

The reconstitution of hematopoietic cells and in vitro assays of immunologic function have been followed in leukemic patients after conventional bone marrow transplantation (BMT) (N = 34) and T-cell depleted BMT (N = 52) from human leukocyte antigen (HLA)-identical sibling donors. No effects of the T-cell depletion could be seen on the recovery of myeloid or lymphoid cells as measured by the day to engraftment or by the absolute number of cells through day 100. Normal numbers of lytically active natural killer cells returned the earliest and were rapidly followed in both groups of patients by the appearance of circulating B cells and normalization of the responses to B-cell mitogens. However, the recovery of normal T-cell proliferative responses were more delayed in recipients of T-cell depleted grafts. Significant quantitative differences were seen only during the first 3 months after transplantation. Neither the number of CD3+ T cells nor the ratio of CD4:CD8 positive cells differed markedly between the two transplant groups. Mitogen-induced immunoglobulin production by peripheral blood lymphocytes (PBL) from patients following T-cell depleted BMT was quantitatively less than that of conventional marrow recipients through the first year, with low normal IgM production reached by 4 to 6 months in both groups. IgG production reached low normal 7 to 9 months after conventional BMT but did not remain at this level until 1 year following either type of transplant. Assessment of the incidence of infections from the day the absolute neutrophil count reached 500 until day 180 after transplant revealed no significant differences between the two groups; indeed, the overall nonleukemic mortality was higher in the recipients of conventional bone marrow. Thus, in our series, the removal of mature cells from the marrow graft did not affect the rate or degree of recovery of myeloid and lymphoid cells but did affect the regeneration of in vitro T-cell dependent functions. We noted early quantitative differences and a delay in the normalization of the T-cell functions measured rather than prolonged absolute deficiencies. The in vitro deficiencies did not result in significant clinically apparent differences between the two groups.