Fig. 3

HCQ inhibitory capacity is specific and has limited cytotoxic effects. a Purified CD4⁺ T cells were cultured in different concentrations of HCQ (1 × = 600 ng/ml), as indicated, and activated with ionomycin (1 μg/ml) for 6 hours. Flow cytometry was used to measure CD4 expression (n = 9). b Effective concentrations of HCQ on CD154 expression were determined by the calculation of the half-maximal effective concentration (EC50) from the flow cytometric results. Inhibitory ability of HCQ relative to vehicle control was determined by plotting to determine the EC50. c, d CD4⁺ T cells and Jurkat cells were pretreated with various concentrations of HCQ (1 × = 600 ng/ml) for 24 hours and then loaded with a MTT reagent. After incubation for at least 2 hours, the absorbance at 492 nm was recorded by spectrofluorometry to obtain the half-maximal cytotoxic concentration (CC50) values. These results were shown as mean ± SEM and represent one assessment; more than six independent experiments had similar results. HCQ hydroxychloroquine, NEG no HCQ treatment