Decreased insulin-like growth factor-I receptor sites on circulating mononuclear cells from children with acute leukemia

Insulin-like growth factor-I (IGF-I) is a known mitogen for various cell types, including those of the hematopoietic cell system. To study the role of IGF-I in the neoplastic process of leukemia in children, the authors have determined the number of IGF-I binding sites on circulating mononuclear cells of children with acute leukemia as compared to normal children, using binding assays. The IGF-I binding sites per cell on peripheral mononuclear cell of children with leukemia decreased compared to those of the control group (411 ± 73 and 1334 ± 227, respectively, p < .001), while their affinity increased (K(d) = 0.14 ± 0.04 and 0.43 ± 0.16, respectively, p = .05). Furthermore, in the patients, the number of the IGF-I binding sites was significantly lower in the subgroup of the peripheral mononuclear cells, which included lymphocytes and monocytes, as compared to their number in the peripheral blast cells (254 ± 43. 6 and 536 ± 98.6, respectively, p =. 02). A significant reduction was found in serum GHBP levels in the patients as compared to the controls (28.21 ± 1.93 and 35.83 ± 2.90, respectively, p = .02), while serum IGF-I and growth hormone levels were similar in patient and control groups. These results suggest a possible involvement of IGF-I in childhood acute leukemia, but further studies are needed to establish whether IGF-I plays a role in this disease.