Biomedical subjects
Publications and source records attributed to C Tassi.
Preliminary experiments were performed in order to identify specific IgM antibodies in human hydatid disease by E.L.I.S.A. method with peroxidase-conjugated anti-human IgM antibodies.
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The activity of thymus-dependent serum factor SF was significantly lower in 18 children wit Down's syndrome (DS) than in 14 matched controls. The percentage of circulating T lymphocytes forming E-rosettes was also low in DS. Together with the previous finding of immature of T lymphocytes in peripheral blood, the present data suggest that the basic immune defect of DS is failure in differentiation of peripheral post-thymic precursors to fully immunocompetent T lymphocytes resulting from lack of thymic hormonal factors.
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The sialic acid content in hamster cells primarily transformed by adenovirus was found lower than in cells transformed by papovavirus SV40. Intermediate concentrations were shown in a cell strain transformed by an adenovirus-SV40 hybrid. An adenovirus 19 - transformed cell strain derived from the NIL-2 hamster cell line, adapted to unlimited growth in vitro prior to the exposure to the adenovirus, revealed a high content of sialic acid. The concentration of sialic acid in cells transformed by DNA-viruses may depend both on the transforming virus and on the preceding history of the cell line. The tumors revealed more sialic acid than the in vitro cultures derived from the same cell strains. This finding is discussed.
3 or 4 antigenic SV40 specific components were established in hamster tumors induced by SV40-transformed cells, using linear sucrose gradient centrifugation and Sephadex G-200 column chromatography. The lightest component, approximate molecular weight 21,000, did not inhibit the nuclear staining of SV40-transformed cells in the fluorescent antibody inhibition test.
BACKGROUND: After the removal of the buffy coat, packed red cell (RBC) transfusion units still contain white cells that may undergo apoptosis as a result of storage conditions (1-6 degrees C). The aim of the present study was the evaluation of this phenomenon in view of the possible influence it may have on febrile nonhemolytic transfusion reactions. STUDY DESIGN AND METHODS: Three independent methods (microscopy, DNA electrophoresis, and cytometry) were used to evaluate apoptosis in white cells present in 13 RBC units. Of these units, 10 had been collected into CPD/saline-adenine-glucose-mannitol and 3 into CPDA-1; each bag was split in two parts, one of which was irradiated. RBCs were stored at 1 to 6 degrees C, and samples were periodically withdrawn for study. The proliferative capacity of stored lymphocytes was evaluated after phytohemagglutinin stimulation and tritiated thymidine incorporation. RESULTS: Apoptosis was found to occur in both granulocytes and lymphocytes, starting from the first 48 to 72 hours of storage. The choice of the anticoagulant-preservative solution and the effect of irradiation did not influence the amount and the timing of the apoptotic phenomenon. Lymphocyte proliferative capacity was found to decrease sharply with storage time. CONCLUSION: Conditions of storage in RBCs induce consistent apoptosis in residual white cells. The possible clinical implications of the relationships between apoptosis and the induction of biologic response modifiers (that may cause interleukin-mediated febrile non-hemolytic transfusion reactions) and between apoptosis and immune reactions remain to be elucidated.
The localization of the SV40 T antigen in hamster cells transformed by the PARA(3ct)-adenovirus 7 variant and, for comparison, by SV40 was examined. The H50 cell strain (transformed by SV40) and the P7-/BL/SV/OD strain (transformed by PARA(3ct)-adenovirus 7) showed a preferential localization of the SV40 T antigen in the nucleus both by immunofluorescence and by complement fixation. On the other hand, two different PARA(3ct)-adenovirus 7-transformed cell lines (P7-/Ar/d/15A and P7/Ar/m/14A) showed an almost equivalent concentration of the SV40 T antigen in the nucleus and in the cytoplasm both by immunofluorescence and complement fixation. The H50, P7-/BL/SV/3D, P7/Ar/m/14A cells were oncogenic for hamsters; the P7/Ar/d/15A line was not.
The mixed lymphocyte reactions are usually performed by the uptake of 3H thymidine (3H TdR) in the study of histocompatibility for allogeneic bone marrow transplantation. Bromodeoxyuridine (BrdUrd), an analogue of thymidine, can be used as an alternative marker of proliferation. In this study we compared the evaluation of the proliferative activity of alloreactive lymphocytes in MLR by 3H TdR and BrdUrd incorporation in flow cytometry. The results show that BrdUrd is able to recognize proliferative activity at least 24-48 hours before 3H TdR, and allows discrimination of proliferation of a few cells despite its proximity to the autologous controls. However, the large quantity of cells needed for every combination is presently a disadvantage of the method.
An assay based on the inhibition of the cloning capacity in a plasma clot semisolid medium assay has been used to test the sensitivity of the Raji cell line to lymphokine-activated killer (LAK) cells. This method overcomes some limitations intrinsic to the widely employed 51Cr release assay and always shows a higher degree of sensitivity. No inhibition of colony growth was found when the effector cells were plated without prior pre-incubation with interleukin 2 or with the addition of the medium derived from the LAK cells. Though more time-consuming than the classic 51Cr release assay, this technique does not require radioactive material. This test may be suitable for a more precise evaluation of LAK activity and for the study of the mechanisms involved in cell killing.
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