Expansion by folinic acid of the peripheral blood progenitor pool after chemotherapy: its use in autografting in acute leukaemia

Abstract

We have tested folinic acid (FA) for ability to increase peripheral blood stem cells (PBSC) after chemotherapeutic aplasia in acute leukaemia. Five adult patients (four AML, one ALL) entered the study, each patient underwent two series of three leukapheresis, the first following induction chemotherapy and the second following the first course of consolidation. The first leukapheresis of each series was done when the white blood cell count reached 10(9)/l with subsequent leukapheresis every other day. Folinic acid (Lederle Laboratories, France) was administered at a dose of 50 mg (i.v.) per day, 15 days from initiation of chemotherapy and continuing through the third leukapheresis of the series (days 25-30). PBSC were collected on a Haemonetics V50 cell separator. In these five cases we observed an increased yield of both colony-forming units, granulocyte macrophage (CFU-GM) and burst forming units-erythroid (BFU-E) expressed per ml of cytapheresis product: CFU-GM x 18, BFU-E x 3 and if expressed per 10(4)/kg of body weight: CFU-GM x 30, BFU-E x 3 (CFU-GM P less than 0.05, BFU-E less than 0.01). Long-term blood culture (LTSC) from FA stimulated leukapheresis, in an attempt to quantitate the most primitive stem cells, demonstrated that this expansion of the PBSC was sustained in time. We found by means of LTSC that FA did not stimulate CFU-L from patients with AML (two cases tested). Finally two AML patients were grafted with FA-PBSC after Cytotoxan and total body irradiation (TBI). Haematopoietic reconstitution was rapid complete and sustained in time in both patients. This indication for folinic acid should be further studied with or as an alternative to haematopoietic growth factors.