To the Editor:—
The data of Race et al in the Jan 11 issue of The Journal (187:150) may be interpreted differently. The occurrence of reticulocytosis after injection of tumor fluid into two normal rabbits is not necessarily evidence of a true erythropoietic effect,1 but rather may reflect the development of a hemolytic state in those animals because the foreign protein extract contained heterologous antibodies to their red blood cells (RBC). It is unfortunate that no information on the RBC count, or hemoglobin or hematocrit levels was given to permit interpretation of the reticulocyte data. In addition, normal animals are poor subjects for the demonstration of erythropoietin2 because of their insensitivity to administered hormone. Starved or polycythemic mice would have been better test animals for assay of any hormonal activity.3 In view of the reported thrombocytosis which developed in the rabbits, it would have been of
Lorber M. Hematopoiesis and Cerebellar Hemangioblastoma. JAMA. 1964;187(12):963. doi:10.1001/jama.1964.03060250081033
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