The leucocyte adhesion molecule-1 (LAM-1) is the human homologue of the murine peripheral lymph node homing receptor, MEL-14, and might play a crucial role in neutrophil localization at inflammatory sites. We have reported previously that recombinant human granulocyte colony-stimulating factor (rhG-CSF) stimulates or enhances several neutrophil functions in vivo, as well as in vitro. To further explore the possible role of G-CSF in inflammation we studied the effect of rhG-CSF on the surface expression of LAM-1 on human neutrophils, both in vitro and in vivo. The expression of LAM-1 by human neutrophils was investigated by indirect immunofluorescence using flow cytometry and monoclonal antibodies anti-Leu-8 and TQ1. A whole blood analysis was performed to minimize in vitro manipulation. Most circulating human neutrophils expressed LAM-1 on the cell surface. Brief exposure of neutrophils to rhG-CSF in vitro decreased the surface expression of LAM-1. rhG-CSF down-regulated neutrophil LAM-1 expression in a time- and dose-dependent manner. Neutrophils from healthy volunteers and from patients who were receiving rhG-CSF exhibited a decreased expression of LAM-1 after rhG-CSF administration, and the expression thereafter returned or overshot the pretreatment level after stopping rhG-CSF administration. These findings indicate that rhG-CSF down-regulates the surface expression of LAM-1 on human neutrophils in vivo, as well as in vitro, and G-CSF might participate in neutrophil-endothelial cell interaction in inflamed tissue.

We studied the impact of clonality, determined by analysis of Epstein-Barr virus genome termini, T-cell receptor genes and clonal chromosomal abnormality, on the clinical outcome in 32 patients with hemophagocytic lymphohistiocytosis (HLH). Of the cases studied, 23 cases were EBV-clonal, 15 cases were TCR-clonal and 7 cases were cytogenetically clonal. Thirty patients were treated with immuno-chemotherapy and/or multiagents' chemotherapy and 4 received bone marrow transplantation. All 7 cases, in which cytogenetically abnormal clones were identified, were fatal (3-year survival by Kaplan-Meier analysis; 14%, 95%CI: 0-40%). None of these 7 cases received bone marrow transplantation. On the other hand, the 3-year survival of 23 clonal EBV-positive HLH cases including 4 cytogenetically abnormal cases was 64 % (95%CI: 42-84%), while that of 15 TCR-clonal cases was 53% (95%CI: 26-78%). Our observations suggest that cytogenetically abnormal cases are at extremely high risk, requiring intensive immuno-chemotherapy followed by prompt and timely allogeneic bone marrow transplantation.

Delay of the initial lumbar puncture and intrathecal injection of chemotherapy seems to be feasible in children with ALL. Further controlled evaluations are needed to establish the validity of this conclusion.