Mobilization and selection of peripheral blood hematopoietic progenitors in children with systemic sclerosis.

BACKGROUND AND OBJECTIVE

Autologous transplant of lymphocyte-depleted peripheral blood stem cells has been proposed for treatment of patients with severe autoimmune disease. However, until now, no data are available on the safety and feasibility of both stem cell collection and selection in pediatric patients with these disorders. We report on three children affected by systemic sclerosis with lung involvement, who received chemotherapy and granulocyte colony-stimulating factor (G-CSF) to mobilize autologous peripheral blood progenitors.

DESIGN AND METHODS

The priming regimen consisted of cyclophosphamide (CY, 4 g/m(2)) and G-CSF (lenograstim, 10 microg/kg/day starting 2 days after cyclophosphamide administration until stem cell collection). Leukapheresis was performed when WBC and CD34+ cell count were at least 2 x 10(9)/L and 0.03 x 10(9)/L, respectively. In the first patient, positive selection of CD34+ cells was performed through the Ceprate SC stem cell concentrator (CellPro, Bothell, WA, USA). In the remaining 2 children, progenitor cells were also purged with negative selection of CD4+ and CD8+ lymphocytes performed by means of the Isolex 300i device (Baxter).

RESULTS

All patients tolerated the priming regimen well and did not present any sign of autoimmune disease exacerbation. Collection was successful in all children and the number of CD34+ cells before selection ranged between 10.7 x 10(6) and 17.6 x 10(6)/kg of patient body weight. The selection of haematopoietic stem cells in the 3 patients resulted in at least 2. 6-log T-cell depletion of the cell content, with a recovery of the initial value of CD34+ cells comprised between 21 and 44%. After, a preparative regimen consisting of CY (200 mg/kg over 4 days) and Campath-1 G in vivo (10 mg/day for 2 consecutive days), patients were transplanted using cryopreserved lymphocyte-depleted progenitor cells. In all cases, a prompt hematopoietic engraftment was observed.

INTERPRETATION AND CONCLUSIONS

Taken together these data suggest that mobilization, collection and selection of hematopoietic progenitors are safe and feasible in children with autoimmune disease.