Stimulation of PB MNC cells of ALL patients with PHA was also examined by Ridgway et al. The authors have shown that the production of GM-CSF and IL-1 by the PHA-stimulated PB MNCs of paediatric ALL patients receiving maintenance chemotherapy was diminished as compared to the control, suggesting that PHA may damage key cytokine-production mechanisms [38]. Here, CSF2 is linked to acute lymphoblastic leukemia.