Fig. 1

Low neutrophil count and increased neutrophil chemotaxis correlate in APL patients treated with ATO. The leukocyte count (A) and absolute neutrophil count (ANC) (B) were reduced during ATO treatment (at days 4-5 and days 22-25) compared to before treatment (day 1). When only on treatment with ATRA (week 6), there was no decrease in leukocyte and absolute neutrophil counts. Chemotaxis of neutrophils isolated from subjects at different time points during treatment with ATO and ATRA and from healthy donors are presented as percent migrated cells (C) and velocity at half-maximum migration time (D). Migration and velocity are decreased before treatment compared to healthy donors, indicating a reduced chemotactic ability. The correlation between leukocyte count and chemotaxis (E) and ANC and chemotaxis (F) was examined using Spearman´s test of correlation. There was a negative correlation, indicating that a lower leukocyte count or ANC was correlated with increased chemotaxis. Levels of ATO measured in plasma collected from study subjects and healthy donors presented as µM/L (G). There was an increase in ATO levels in study subjects during ATO treatment (days 5 and 22-25) compared to before treatment and in healthy donors. Since the migration of unstimulated cells was subtracted from the fMLF-induced migration to calculate percentage migration, some of the values reported fell below 0, due to the unstimulated value reaching a higher total migration than the examined condition (C, E, F)