CHAPTER 5 



LYMPHOCYTIC LIFE SPAN 

 AND TURNOVER 



JESSE L. BOLLMAN 



Lymphocytes are formed in several sites in the body from which they 

 migrate into the blood and lymph. The life span of the lymphocytes would 

 be the total number of body lymphocytes divided by the average of the 

 numbers formed in each tissue each day. Another method for the determina- 

 tion of life span is the administration of labeled lymphocytes with subse- 

 quent determination of the rate of disappearance of the labeled lymphocytes 

 from the blood, lymph, and tissues. A third method involves the drainage 

 of lymphocytes from the body via a lymphatic fistula and the calculation 

 of the decrease of the lymphocytes in the blood. There are modifications 

 and combinations of the above methods. Each method, however, has several 

 complicating factors which, in addition to the technical difficulties, include 

 different rates of formation and destruction of lymphocytes in the differ- 

 ent tissues, the circulation of lymphocytes from the blood, lymph, and tis- 

 sues, and the reutilization of labeled material, either by division of the 

 lymphocytes or reutilization in new lymphocytes. At the present time we 

 can only give an approximation of the life span of lymphocytes, and even 

 on the approximation there is a diversity of opinion. 



The bone marrow is most rich with lymphocytes. Yoffey and Courtice 1 

 counted 300,000 lymphocytes per cubic millimeter from guinea pig bone 

 marrow and estimated that the total number was between ten and twenty 

 times that of the blood. By counting the number of cells in visible phases 

 of mitosis, Widner et air calculated, on the basis of 25 minutes' duration 

 for mitosis as observed, that the cells of the bone marrow of the rat were 

 completely renewed in from 1.4 to 4.4 days. 



Yoffey,' 5 Kindred, 4 and I 4a have observed that a large number of labeled 



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