Pre-irradiation haematological effects of the bacterial extract Broncho-Vaxom and postirradiation acceleration recovery from radiation-induced haematopoietic depression.

Effects of the bacterial extract Broncho-Vaxom (BV), free of endotoxin, on haematopoietic parameters of peripheral blood, bone marrow, spleen and thymus were investigated in normal and irradiation-myelosuppressed C57BL/6 mice. BV in normal (nonirradiated) mice induced transient lymphocytopenia and increased granulocytes, particularly neutrophils, six to nine hours after administration. Elevated numbers of peripheral blood macroreticulocytes were observed during the third hour. In the splenic red pulp, enhancing haemopoietic activity, foci of fibroblasts began to appear more frequently from the first hour to 24 h. In lymphatic follicles of the spleen and thymus, the incidence of macrophages or monocytes began to increase three hours after BV application. Twenty-four hours later thymus weight decreased by 27%. In the bone marrow, enhanced proliferation of eosinophils was observed from hour nine, with maximum proliferation at hour 24. BV treatment 24 h before irradiation had a notable radio-protective effect, manifested by accelerated haemopoietic recovery during the postirradiation period. Accelerated myelopoiesis, erythropoiesis and megakaryocytopoiesis resulted in accelerated peripheral blood recovery. However, BV had no effect on thymus reparation as suggested by similar effects in BV protected and BV nonprotected animals during the entire period which followed a 6.5 Gy dose.