BCP-ALL cells use TNTs to drive cytokine release within the microenvironment. (A) IP10/CXCL10 supernatant levels in coculture of primary leukemic patient ALL#7 cells with primary MSC#1 (left panel), MSC#2 (middle panel), or MSC#3 (right panel). TNT signaling was inhibited by gentle shaking or culture in a transwell system (1-tailed t test, unpaired). (B) Same as panel A for IL8 levels. (C) Same as panel A for MDC (CCL22) levels. (D) Same as panel A for TARC (CCL17) levels. (E) IP10/CXCL10 supernatant levels in coculture of primary leukemic patient ALL#9 cells with primary MSC#4 (left panel) or MSC#5 (right panel). (F) Same as panel E for IL8 levels. (G) Same as panel E for MDC (CCL22) levels. (H) Same as panel E for TARC (CCL17) levels. Data are means ± SEM; *P ≤ .05, **P ≤ .01. nd, not detectable (below detection level) (see also supplemental Figure 9).