Figure 2
Integrin alpha4 blockade sensitizes primary pre-B ALL cells to chemotherapy. (A) LAX7R cells were plated on bovine serum albumin (BSA) as control or humanVCAM-1 and treated with control IgG4 or anti-alpha4 mAb (NZM). Numbers of viable adhering cells were counted after 48 hours. (B) Cell viability was determined by Trypan blue exclusion of dead cells. NS, nonsignificant (P > .05). (C) LAX7R cells were plated for 3 days on BSA as control or VCAM-1+ and treated with control Ig or anti-alpha4 mAb (NZM) with or without vincristine, dexamethasone, and L-asparaginase (VDL). Depicted is the cell viability by Trypan blue exclusion. *P = .0001 for IgG4+VDL vs NZM+VDL, incubated on VCAM-1–coated plates, mean ± standard deviation (SD), unpaired two-tailed t test, three independent experiments performed in triplicates. (D) Bioluminescent imaging of mice transplanted with LAX7R cells and treated with Ig (n = 4), NZM (n = 4), VDL+Ig (n = 9), or VDL+NZM (n = 9) on day 34, day 57, and day 71 after leukemia cell transfer. A mouse with no leukemia injection treated only with luciferin at time of imaging was included as background control (Ctrl). (E) Kaplan-Meier survival curve was analyzed and MST was calculated for each group: Ig (MST = 38 days), NZM (MST = 52 days), VDL+Ig (MST = 74 days), VDL+natalizumab (euthanized at the end of follow-up, day 151 after leukemia injection). (F) The absence of human LAX7R cells in spleen (SPC) and BM of the VDL+natalizumab group was determined by flow cytometry using an anti-human CD45 Ab. (G) Tissues, including SPC, BM, liver, and lung from two groups were stained with anti-human CD45 antibody by immunohistochemistry (brown). (H) The presence of murine and human DNA in SPC and BM was evaluated using genomic PCR for murine HPRT (hypoxanthine phosphoribosyltransferase) and human glyceraldehyde-3-phosphate dehydrogenase (GAPDH), respectively. (I) Homing of ALL cells to tissues was assessed by CFU assay. (J) Quantified number of colonies. *P < .05, mean ± SD (unpaired two-tailed t test). NS, nonsignificant (P > .05).

Integrin alpha4 blockade sensitizes primary pre-B ALL cells to chemotherapy. (A) LAX7R cells were plated on bovine serum albumin (BSA) as control or humanVCAM-1 and treated with control IgG4 or anti-alpha4 mAb (NZM). Numbers of viable adhering cells were counted after 48 hours. (B) Cell viability was determined by Trypan blue exclusion of dead cells. NS, nonsignificant (P > .05). (C) LAX7R cells were plated for 3 days on BSA as control or VCAM-1+ and treated with control Ig or anti-alpha4 mAb (NZM) with or without vincristine, dexamethasone, and L-asparaginase (VDL). Depicted is the cell viability by Trypan blue exclusion. *P = .0001 for IgG4+VDL vs NZM+VDL, incubated on VCAM-1–coated plates, mean ± standard deviation (SD), unpaired two-tailed t test, three independent experiments performed in triplicates. (D) Bioluminescent imaging of mice transplanted with LAX7R cells and treated with Ig (n = 4), NZM (n = 4), VDL+Ig (n = 9), or VDL+NZM (n = 9) on day 34, day 57, and day 71 after leukemia cell transfer. A mouse with no leukemia injection treated only with luciferin at time of imaging was included as background control (Ctrl). (E) Kaplan-Meier survival curve was analyzed and MST was calculated for each group: Ig (MST = 38 days), NZM (MST = 52 days), VDL+Ig (MST = 74 days), VDL+natalizumab (euthanized at the end of follow-up, day 151 after leukemia injection). (F) The absence of human LAX7R cells in spleen (SPC) and BM of the VDL+natalizumab group was determined by flow cytometry using an anti-human CD45 Ab. (G) Tissues, including SPC, BM, liver, and lung from two groups were stained with anti-human CD45 antibody by immunohistochemistry (brown). (H) The presence of murine and human DNA in SPC and BM was evaluated using genomic PCR for murine HPRT (hypoxanthine phosphoribosyltransferase) and human glyceraldehyde-3-phosphate dehydrogenase (GAPDH), respectively. (I) Homing of ALL cells to tissues was assessed by CFU assay. (J) Quantified number of colonies. *P < .05, mean ± SD (unpaired two-tailed t test). NS, nonsignificant (P > .05).

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