Effect of orally administered heat-killed Enterococcus Faecalis FK-23 preparation on neutropenia in dogs treated with cyclophosphamide.

Dogs injected intravenously for 3 days with cyclophosphamide (CY) at a dose of 10 mg/kg were given 100 mg/kg of Enterococcus faecalis FK-23 preparation (FK-23) perorally for 14 days to confirm the beneficial effects of the latter drug in neutropenic dogs when orally administered. Although FK-23 treatment did not inhibit CY-induced neutropenia, it augmented neutrophil-reconstituting capacity in these dogs. Increases in the myeloid/ erythroid ratio and neutrophilic lineages were found in the bone marrow of FK-23 administered dogs. The oral administration significantly restored the reduced activity of neutrophil phagocytosis and chemiluminescence in dogs treated with CY. These findings indicate that FK-23 administered perorally not only augments neutrophil reconstitution through the activation of bone marrow but also functions in dogs treated with CY. It may thus be a useful supportive agent to reduce the adverse side-effects associated with the administration of chemotherapeutic agents such as CY.