Trial Information

Neutrophil Extracellular Traps (NETs) Formation Post-hematopoietic Stem Cell Transplantation (HSCT) and Its Relation to Chemotaxis and Creation of Reactive Oxygen Species

Although neutrophil engraftment takes place 10 to 14 days after autologous HSCT, and 15 to
30 days after allogeneic HSCT, using an ablative conditioning regimen, neutrophil
dysfunction may persist for longer periods. Relatively scant data exists on neutrophil
function following HSCT. After autologous HSCT, the respiratory burst and phagocytosis may
be decreased for up to 3 months. After allogeneic HSCT, respiratory burst and chemotaxis are
generally decreased for 4 to 6 months. Factors such as continuation of chemotherapy,
immunosuppression, and GVHD contribute to this prolonged dysfunction. No data exist on
reconstitution of NETs following HSCT.

Nets production and other neutrophil functions will be examined at several time points:
before transplantation, at neutrophil engraftment, 6 weeks, 3 months, 6 months, 9 months, 1
year, 1.5 years, 2 years, and 3 years post-transplant, or until normalization of neutrophil
function at 2 consecutive time points. Data gathered on patients will cover:

1. Demographics.

2. Tumor histological type, staging, previous chemotherapy regimen, and initial response
to treatment.

3. HSCT procedure - type of conditioning regimen, type of graft (autologous or
allogeneic - related donor/unrelated donor/cord blood), use of bone marrow stem cells
(SCs) or peripheral mobilized SCs, number of SCs given, post-transplant
immunosuppression, post-transplant prophylactic antimicrobial treatment, infections
during the study period, and GVHD occurrence and treatment.

Neutrophil examinations will be done in collaboration with the Laboratory for Leukocyte
Function of the Department of Pediatrics, Meir Medical Center, Kfar Saba and NETs
visualization with the Department of Cellular Microbiology at the Max Planck Institute for
Infection Biology, Berlin.