EARLY CALCIUM SIGNALING AND CALCIUM REQUIREMENTS FOR THE IL-2 RECEPTOR EXPRESSION AND IL-2 PRODUCTION IN STIMULATED LYMPHOCYTES

Two kinds of lymphocyte populations were prepared from human resected tonsils: one was a mixed population consisting of T cells, B cells, ot her lymphocytes, and a few macrophages, and the other was a T-enriched population obtained by removing adherent cells from the mixed populat ion with a nylon wool column, A transient rise in cytosolic free calci um ion concentration ([Ca2+](i)) was observed in both the populations within a few minutes of stimulation with concanavalin A (Con A), Howev er, emergence of cells which had high [Ca2+](i) after 4 min of Con A s timulation was observed practically only in the mixed population, The [Ca2+](i) elevation occurring within a few minutes of stimulation in b oth populations was interpreted as being due to a release from the int racellular Ca-storing organelles, whereas the high [Ca2+](i) in a grou p of cells after 4 min of Con A stimulation in the mixed population wa s caused by an influx of extracellular calcium that probably correspon ds to a transient enhancement of Ca2+ uptake observed only in the mixe d population during early stimulation, Con A induced both interleukin 2 receptor (IL-2R) expression and interleukin 2 (IL-2) production, A n onmitogenic lectin, wheat germ agglutinin (WGA), also induced a rise i n the [Ca2+](i) within a few minutes, WGA induced IL-2 production, but did not induce IL-2R expression, Chelation of extracellular calcium w ith EGTA at the time of Con A addition resulted in a decrease in IL-2R expression, IL-2 production, and DNA synthesis, but not when CaCl2 eq uimolar to EGTA was present in the culture medium, Chelation of calciu m 12 hr after Con A stimulation decreased IL-2R expression, but had no effect on IL-2 production, These results indicate that IL-2 productio n required Ca2+ only in the early (G(0)) stage and that IL-2R expressi on was dependent on Ca2+ in both the G(0) and the G(1) stages. (C) 199 6 Academic Press, Inc.