MOBILIZED CD34-CHAIN AMYLOIDOSIS - RATIONALE AND APPLICATION( CELLS SELECTED AS AUTOGRAFTS IN PATIENTS WITH PRIMARY LIGHT)

BACKGROUND: Concern about tumor cell contamination in stem cell prepar ations has led to the use of CD34+ cell selection as a means of purgin g. Increasing the number of CD34+ cells per leukapheresis may help to provide an adequate dose of CD34+ cells. STUDY DESIGN AND METHODS: The reverse transcriptase polymerase chain reaction (RT-PCR) was employed to clone overexpressed clonotypic immunoglobulin light-chain variable region genes (lg V-L) from bone marrows of patients with primary ligh t-chain amyloidosis (AL). Patient-specific primers were designed to ev aluate stem cell collections for contamination. CD34+ cell selection w as performed on components from AL patients who underwent mobilization with granulocyte-colony-stimulating factor (G-CSF) (filgrastim; 16 mu g/kg/d for 4 days) and collection by large-volume leukapheresis (LVL; 25L) on Days 4 and 5. The selected cells alone were transfused after p atients received mephalan (200 mg/m(2)). RESULTS: Contamination was fo und in collections from 4 to 7 patients, which provided the rationale for a subsequent trial of CD34+ cell selection. The median number of C D34+ cells per kg collected on Days 4 and 5, and in toto, was 4.0 x 10 (6)(1.1-12.7), 7.9 x 10(6)(1.8-12.7), and 10.7 x 10(6)(2.9-25.4), resp ectively (n = 9 patients). The median yield per selection was 38 perce nt, with a purity of 85 percent (45-97%), and the viability of CD34+ c ells averaged 96.4 +/- 3.6 percent (n = 18 selections). The median num ber of CD34+ cells infused was 5.9 x 10(6) per kg (2.1-10.1). In compa rison with AL patients given unselected autografts, patients receiving selected CD34+ cells experienced similar reconstitution of neutrophil s and platelets but slower lymphocyte recovery. CONCLUSION: Patients w ith AL often have contamination with clonotypic cells in their blood a utografts. G-CSF mobilization and LVL provide components that allow th e selection of adequate doses of CD34+ cells. The use of CD34+ cells i n patients with AL achieves rapid neutrophil and platelet recovery but delayed lymphocyte recovery. CD34+ cell selection is feasible in the treatment of AL, but its effectiveness in purging clonotypic cells rem ains to be ascertained.