The effects of gamma-irradiation on haemopoiesis and red blood cell destruction in hamsters infected with Leptospira interrogans serovar ballum.

Irradiated hamsters were infected with Leptospira interrogans serovar ballum in order to study the effects of impairment of the reticulo-macrophage system on the progression of the disease and the development of haemoglobinaemia. Infected and irradiated hamsters were compared with infected controls, irradiated controls and untreated controls. Red blood cells (RBCs) from untreated controls were biconcave disks while those from irradiated controls were echinocytes. Red blood cells from animals of both infected groups which were severely affected and moribund were in the form of pitted spherocytes and were associated with increased icteric indices and haemoglobinaemia. Red blood cells from less severely affected animals were echinocytic. Pitted spherocytes, however, were seen in some irradiated-infected hamsters before increased icteric indices and haemoglobinaemia were present. Both irradiated-infected and irradiated hamsters showed severe depletion of haemopoietic cells and lymphoid cells, with regeneration occurring in those animals which survived for longer. Red cell sequestration and erythrophagocytosis were present in infected-only hamsters. In irradiated-infected animals, severe anaemia was caused by both persistence of fixed macrophages, RBC sequestration and erythrophagocytosis, and haemorrhage due to vascular damage and renal papillary necrosis. A severe leucopaenia affected the irradiated hamsters' ability to suppress leptospiral multiplication resulting in the presence of larger numbers of organisms.