Disorders that resemble lymphomas.
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Adult↗
Biomedical subjects
B Yirinec
Publications and source records attributed to B Yirinec.
Comparison of the effects of 1,25-dihydroxyvitamin D3 on T lymphocyte subpopulations.
Previous studies have demonstrated that 1,25-dihydroxyvitamin D3 (calcitriol) is a potent inhibitor of human T lymphocyte proliferation. It has been reported that only CD4+ cells are sensitive to the anti-proliferative action of calcitriol. To further evaluate this observation, we first performed cell cycle analysis of unfractionated phytohemagglutinin-stimulated peripheral blood mononuclear cells (PBMC) in the absence or presence of calcitriol. The CD4/CD8 ratio was similar between control and treated cells for each phase of cycle (G0----G1, S, G2 + M), suggesting that calcitriol did not selectively block proliferation of either T cell subpopulation. Secondly, the growth-inhibitory activity of calcitriol on PBMC selectively depleted of either CD4+ or CD8+ cells was comparable to that observed with unfractionated PBMC. Furthermore, the induction of transferrin receptors was inhibited by calcitriol to a comparable degree in each T cell subset, suggesting that equivalent inhibition of transition into late G1 was observed. Finally, calcitriol inhibited the proliferation of highly purified T cell subsets (greater than 99% pure) to equivalent degrees. These data suggest that T cell subsets defined by either the CD4 or by the CD8 antigen are both sensitive to the growth inhibitory effects of calcitriol.
Antibodies, Monoclonal↗
Effect of alterations in the size of the vacuolar compartment on pinocytosis in J774.2 macrophages.
J774.2 macrophages cultured in medium containing 10 mg/ml sucrose accumulate the sugar by pinocytosis and become highly vacuolated, due to the sugar's osmotic effect within the vacuolar compartment. When such cells are incubated in medium containing 0.5 mg/ml invertase, the enzyme reaches the sucrose vacuoles by pinocytosis, then cleaves the sugar to more permeant monosaccharides. Within 4 hours, the vacuoles shrink to smaller, phase-dense organelles (Cohn and Ehrenreich, 1969, J. Exp. Med., 129:201). We have used this reversible expansion of the lysosomal compartment to address two questions: (1) Does the increased size of the lysosomal compartment affect pinocytic accumulation of solute, and (2) what is the fate of the vacuolar membrane and its soluble content during invertase-induced vacuole shrinkage? Using lucifer yellow (LY) as a probe for pinocytic fluid influx and efflux, we found that vacuolated cells accumulated 30-50% less LY than controls and returned to higher rates of pinocytosis after invertase-induced vacuole shrinkage. A similar reduction in LY accumulation was achieved after feeding cells latex beads to increase the size of the lysosomal compartment. Thus, treatments that increased the size of the lysosomal compartment reduced solute accumulation via pinocytosis. A dramatic shrinkage of LY-containing sucrose vacuoles followed pinocytosis of invertase. Despite this reduction in size of the LY-containing vacuoles, the overall rate of LY efflux did not increase significantly during invertase-induced vacuole collapse. Electron microscopy revealed that during shrinkage, the excess vacuolar membrane was compressed into whorled membranous organelles (residual bodies), with fluid markers (colloidal gold and, by inference, LY) trapped inside. The trapping of LY inside lysosomes as J774.2 macrophages returned to their normal dimensions indicates that nearly all of the surplus membrane contents were removed from circulation as well.
Cells, Cultured↗