Cytochemistry of the Lymphocytes 45 



dase activity with the method employed.""' 



Dehydrogenases. Succinic dehydrogenases is demonstrable in the cyto- 

 plasm of the lymphocytes in normal blood 105, 106 and lymphatic tissue. 15, 16, 

 73, 89, 96 Although other investigators have failed to demonstrate dehydro- 

 genase activity in lymphatic tissue,-'' Tn the lymphocytes exhibit one to 

 several fine, purplish granules in their cytoplasm following incubation in 

 buffered neotetrazolium. 106 Nitro BT appears to be a more sensitive sub- 

 strate and permits better localization of dehydrogenase activity in the lym- 

 phocytes than is obtained with neotetrazolium in the blood and lymphatic 

 tissue (spleen) , 78 In lymphatic tissues (lymph nodes and tonsils) the neo- 

 tetrazolium reaction reveals dehydrogenase activity in about half of the lym- 

 phocytes. 10 "' The nitroneotetrazolium chloride (NNT) substrate yielded 

 negative reactions when applied to the spleen even after using an extended 

 time in incubation. 75 Marked variations in dehydrogenase activity of the 

 lymphocytes in chronic lymphocytic leukemia have been observed. 1 " 5 The 

 percentages of reactive lymphocytes in ten cases of chronic lymphocytic leu- 

 kemia were as follows: one case w r ith 40 per cent, six cases with 2 to 5 per cent, 

 two cases with over 90 per cent, and one case with no lymphocytes exhibiting 

 dehydrogenase activity. 105 Dehydrogenase activity demonstrated with 2,3,5- 

 triphenyl tetrazolium chloride (TTC) as the substrate reveals no appre- 

 ciable activity with only a few T fine formazan crystals in the lymphocytes in 

 the follicles and pulp of the normal lymph node. 10 In contrast to the normal 

 cells, the lymphocytes in lymphocytic leukemia and lymphosarcoma reveal 

 active reduction of formazan, indicating increased enzyme activity in these 

 abnormal cells. 1,; Lymphocytes in the perifollicular and pulp areas of the 

 normal spleen exhibit several fine and coarse formazan granules in their 

 cytoplasm while the immature cells of the nodules exhibit less dehydrogenase 

 activity. 15 The endogenous dehydrogenase activity of the lymphocytes, par- 

 ticularly in the perifollicular areas, is increased in hypersplenism. 15 By apply- 

 ing a modified nitro BT procedure to normal and leukemic lymphocytes of 

 the blood, dehydrogenase activity has been observed in the lymphoid cells of 

 lymphosarcoma (Fig. 3-36) and to a lesser extent in lymphoblastic leu- 

 kemia. 9 Normal lymphocytes (Fig. 3-27) and those of chronic lymphocytic 

 leukemia only rarely exhibited a positive reaction with this procedure. The 

 dehydrogenase activity was localized to the mitochondria. 9 Histochemical 

 demonstration of dehydrogenase activity is a relatively new field. The wide 

 variety of techniques and the use of tetrazolium salts in the study of lym- 

 phoid cells must be evaluated in the light of newer and more sensitive 

 methods. 



Cytochrome Oxidase. Between 5 and 20 granules reacting with indo- 

 phenol blue are demonstrable in the cytoplasm of the lymphocytes in the 



