Abstract
These experiments attempted to analyze more closely the nature of the characteristic cellular reaction occurring in the tissues in kalaazar. The hamster Cricetulus griseus, a, variety of Chinese field mouse, which has been shown to be highly satisfactory for this purpose, was used. 1
Our first observations were upon the blood obtained by splenic puncture from both normal and infected animals. Differential counts upon preparations supravitally stained with neutral red and janus green by Sabin's technique were made from 20 normals, and 20 infected experimentally with kala-azar, from 10 to 12 weeks. 2 At this time the infection is always well established and the lesions extensive.
The results of these counts are given in the following table.
By this method one has little difficulty in identifying practically all of the cells seen in preparations made from normal animals. The great increase, in unidentified cells in infected animals, is caused by the increase in number of definite type of small, mononuclear cell. which is very actively motile, and which never has been observed to contain kala-azar bodies. As yet we are uncertain as to the exact identity of this cell, but it clearly seems to have nothing directly to do with the propagation or destruction of the Leishmann-Donovan bodies, and in the tissues, forms no specific part of the lesions. The distinction between monocytes and reticulo-endothelial cells of clasmatocytes was based upon their characteristic receptive staining with neutral red, the nionocyte showing a rosette of the dye opposite the “Hof” of the nucleus, while the clasrnatocytes of the splenic reticulo-endothelial system take up the stain in large, irregular globules.
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