U937 and JKT cell lines were cultured with or without MTX (1 uM) and LPS (25 ug/ml). Viability determined by trypan blue dye exclusion was decreased by MTX in U937 but not JKT cell lines (top left). Decreased viability of U937 cells increased over time of incubation with MTX (1 uM) but not with HCQ (1 uM; top right). Forward/side scatter plots show changes consistent with decreased viability of U937 cells after 72 hours of culture with MTX (1 uM) but not with HCQ (1 uM; lower left). Apoptosis measured by 7-AAD was increased in dose- and time-dependent fashion by MTX but was not induced by HCQ (lower right). P values were determined by one-way ANOVA. 7-AAD, 7-amino actinomycin D; ANOVA, analysis of variance; HCQ, hydroxychloroquine; LPS, lipopolysaccharide; MTX, methotrexate.