Surface expression of TNF receptor molecules on BCP-ALL blasts and their modulation upon CD40 ligation. (A,B). The percentage of CD40⁺ and CD27⁺ ALL blasts at diagnosis is higher in low-risk patients. The percentage of BCP-ALL cells positive for CD27 (A) and CD40 (B) surface expression was assessed by flow cytometry in patients (pts) allocated to the low-risk (LR) versus the high-risk (HR) group by standard clinical criteria such as age, leukocyte count, and chemoresistance. (C,D) Ligation of CD40 modulates the expression of other TNF receptor molecules on BCP-ALL blasts. Expression of the TNF receptor molecules in CD40-activated blasts was assessed by flow cytometry after culture of ALL cells on CD40 ligand–expressing feeder cells for 3 to 4 days. CD40 activation is further accompanied by significant down-regulation of CD27 surface expression on blasts both in the LR and HR patient group (C). In accordance with the higher percentage of CD40⁺ blasts in LR patients, this patient group reveals an enhanced capacity to up-regulate CD95 upon CD40 ligation compared with HR patients (P = .013; D). In the box plot diagrams the boxes represent the interquartile range with the line in the middle indicating the 50th percentile. The error bars, or whiskers, represent the highest and lowest values that are not outliers or extreme values.