HCQ inhibits intracellular calcium mobilization in primary T cells.

Peripheral blood T cells from healthy volunteers were pretreated with varying concentrations of HCQ for 18 hours and were then loaded with calcium-sensitive dyes calcium green-1 and fura-red. Cells were stimulated, as indicated by arrow, with (A) biotinylated OKT3 (40 μg/mL) plus avidin (10 μg/mL) or (B) 1 μmol/L ionomycin. Changes in intracellular Ca⁺⁺ concentration (fluorescence) versus time (seconds) were monitored by fluorescence-activated cell sorter, and results are representative of 3 separate experiments.