Adhesion molecules, endogenous granulocyte colony-stimulating factor levels and replating capacity of progenitors in autoimmune neutropenia of childhood.

Aim: To investigate the role of granulocyte colony-stimulating factor (G-CSF) and adhesion molecules and the response of bone marrow to peripheral cytopenia in autoimmune neutropenia of childhood (AIN).

Methods: Thirty-five children with AIN, 25 with acute leukaemia in remission, 10 of whom developed chemotherapy-associated neutropenia, and 28 non-neutropenic age-matched children were studied. The methods included haemopoietic progenitor cells' colony growth, replating of colony-forming unit-granulocyte macrophage (CFU-GM) of the 7th day and ELISA for the detection of serum levels of cytokines and adhesion molecules.

Results: In cases of severe autoimmune neutropenia, haemopoietic progenitors showed increased proliferative capacity compared to the control group (p = 0.03). Intercellular adhesion molecule-1 (ICAM-1), E-selectin, tumour necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) levels inversely correlated with neutrophil counts (r = -0.8, p < 0.001 for ICAM-1, r = -0.5, p = 0.04 for E-selectin, r = -0.58, p = 0.01 for TNF-alpha, r = -0.62, p = 0.04 for IL-1beta). Serum ICAM-1, TNF-alpha and IL-1beta levels correlated positively with G-CSF levels (r = 0.47, p = 0.03 for ICAM-1, r = 0.65, p = 0.01 for TNF-alpha, r = 0.67, p = 0.04 for IL-1beta). Serum G-CSF levels were widely distributed and did not correlate with neutrophil counts (r = -0.44, p = 0.09). In secondary neutropenias the respective levels were lower than those in autoimmune neutropenia.

Conclusions: Haemopoietic progenitors show increased proliferative capacity in cases of severe autoimmune neutropenia. G-CSF seems to act as an inducer of endothelium activation. The degree of neutropenia correlates with serum ICAM-1, E-selectin, TNF-alpha and IL-1beta levels, indicating the existence of an activated endothelium and presumably of a latent, low-grade, inflammatory process in severe autoimmune neutropenia.