Jose Quintans

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Monoclonal antibody GK1.5 recognizes a previously undescribed murine T cell surface molecule, designated L3T4, which migrates on SDS-PAGE under reducing conditions as a single band with an apparent m.w. of 52,000. L3T4 is expressed by approximately 80% of thymocytes and by approximately 20% of spleen cells. There appears to be poor correlation between(More)
Recent studies have proposed that tumor necrosis factor alpha (TNF-alpha) and ionizing radiation induce apoptosis by activating hydrolysis of sphingomyelin to ceramide. Bcl-2 and a related gene, Bcl-X, inhibit several forms of apoptosis. Herein, we report that internucleosomal DNA fragmentation, characteristic of apoptosis and induced by ionizing radiation,(More)
Ionizing radiation mediates cell death, in part, through chromosomal damage following one or more cell divisions. X-rays also induce programmed cell death (apoptosis) in some cell types both in vitro and in vivo. Both neutral and acidic sphingomyelinases, which generate the lipid second messenger ceramide, are reported to induce apoptosis following ionizing(More)
We report that WEHI-231 undergo apoptosis following exposure to the protein kinase C inhibitors chelerythrine chloride and calphostin C. Following the addition of chelerythrine or calphostin C to WEHI-231 cells, ceramide production increased over baseline levels with a concurrent decrease in sphingomyelin. More detailed examinations determined that the(More)
Previous work has demonstrated that down-regulation of ceramide production after selection of cells with N-oleoylethanolamine (OE), an inhibitor of ceramidase, results in resistance to DNA damage-induced apoptosis. We report here that acute exposure of WEHI-231 cells (murine B-cell lymphoma) to OE activates neutral sphingomyelinase, induces ceramide(More)
We demonstrate for the first time how immature B cells kill themselves. Ceramide is identified as the mediator of apoptosis in the murine B lymphoma line WEHI 231 commonly used as a model to study clonal deletion in B lymphocytes. We show that exogenous ceramide induces apoptosis in WEHI 231 cells. To maintain self tolerance, immature lymphocytes readily(More)
Sympathetic nerve endings were destroyed with 6-hydroxydopamine (6-OHDA) and the response to thymus-dependent and -independent antigens compared in 6-OHDA-treated and control mice. A significantly enhanced plaque-forming cell response to 2 thymus-independent antigens was observed in the 6-OHDA-treated mice; in contrast the response to a thymus-dependent(More)
Experimental autoimmune thyroiditis (EAT), which to some extent represents an experimental model of human chronic lymphocytic thyroiditis, is an organ-specific autoimmune disease characterized by autoantibody production to thyroid antigens (Ag) and mononuclear infiltration of the thyroid gland. EAT induced by immunization with human thyroglobulin (hTG) with(More)
Immunization of mice with 50 micrograms human thyroglobulin (TG) in complete Freund's adjuvant leads to histological thyroiditis; production of IgG, IgA, and IgM anti-TG antibodies; and in vitro proliferative responses after incubation of lymphocytes with TG. Oral administration of 500 micrograms TG at four intervals before Tg immunization and once(More)