Dextran sulfate induces changes in the free intracellular calcium ion concentration of a subpopulation of immature thymocytes.
Previous studies have shown that certain sulfated polysaccharides, such as dextran sulfate (DxS), can induce a rapid and sustained increase in the free intracellular calcium ion concentration ([Ca2+]i) of thymocytes, whereas they cannot induce a change in the [Ca2+]i of peripheral lymphocytes. This study examined this phenomenon in more detail and clearly demonstrated that only immature thymocytes can respond to DxS. Cortisone-resistant thymocytes failed to exhibit an increase in [Ca2+]i when exposed to DxS. Furthermore, analysis of [Ca2+]i changes at the single cell level using a flow cytometer demonstrated that only a subpopulation of immature thymocytes responded to DxS. Additional flow cytometry studies revealed that DxS and Con-A induce a [Ca2+]i response in different subpopulations of thymocytes, approximately 30% of thymocytes responding to Con-A and 15-20% to DxS. Thus, responsiveness to Con-A and DxS, in terms of increases in [Ca2+]i, may represent a novel marker for two different thymocyte subpopulations. Such metabolic markers could be used to complement the conventional serological methods currently employed to define stages in thymocyte differentiation.
Weston
S A
SA
Division of Cell Biology, John Curtin School of Medical Research, Australian National University, Canberra.
Tellam
R L
RL
Parish
C R
CR
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003208:Concanavalin A / Q000494:pharmacology; D016264:Dextran Sulfate / Q000494:pharmacology*; D005260:Female; D005434:Flow Cytometry; D007424:Intracellular Fluid / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
D003208:Concanavalin A; D016264:Dextran Sulfate; D002118:Calcium