3H-thymidine autoradiography of CSF cells in primary reticulum cell sarcoma of the brain.

CSF cells in a case of primary reticulum cell sarcoma of the brain with diffuse subarachnoid spreading were examined by 3H-thymidine autoradiography. Immediately after lumbar puncture, the CSF withdrawn was incubated at 37 degrees C for 1 hr with an admixture of 3H-thymidine at a rate of 1 muCi/ml CSF. The cells were collected by centrifugation and the microautoradiographic procedure was performed. The labeling index (L.I.) of the total CSF cells was 10.5%, and when non-neoplastic cells, i.e. polymorphonuclear leukocytes, small lymphocytes, monocytes etc., were excluded, the real L.I. of the tumor cells in the CSF was supposed to be more than 14.4%. Referring to the results of various brain tumors reported in the literature, this belongs to the highest labeling group. The high L.I. of the tumor cells in this case was well consistent with the extremely rapid clinical course. It should be stressed that the examination of CSF cells by 3H-thymidine autoradiography in cases of brain tumors could be one of the valuable methods indicating the DNA synthesis of the tumor cells, which is an important parameter of malignancy.