D. D. JOEL AND E. P. CRONKITE 
891 
1000 
500 
n — I — \ — I — r 
I \ \ I — I — \ — \ — r 
DEPLETION BY ECIL 
r-1 — r 
1 R 
SMALL 
BLOOD LYMPHOCYTES 
(CIRCULATING CELLS PER KILO) 
THORACIC DUCT LYMPHOCYTES 
(OUTPUT PER KILO PER HOUR) 
J \ \ L 
4 6 8 10 12 14 
DAYS AFTER BEGINNING ECIL 
16 
18 20 
Figure 4. — The effect of continuous ECIL on blood lymphocytes and thoracic duct cellular output. Lymphocytes 
are classified as large (• •) or small (O O) according to cell diameter in blood smears and electronically 
Coulter Model F) in thoracic duct lymph. 
output of small lymphocytes. The first com- 
ponent, with a halving time of 1.2 days, 
corresponds to the elimination of an easily 
mobilizable pool of lymphocytes and the second 
component (halving time of approximately 30 
days) corresponds to a more sessile mass of 
lymphocytes. Calculations based on these data 
indicate the size of the easily mobilizable pool to 
be approximately 10 times the number of cir- 
culating blood lymphocytes, or 3-5 X 10® 
lymphocytes/kg body weight.^® 
It is v^ell known that a fraction of blood 
lymphocytes cycles from blood to lymphoretic- 
ular tissues and back again.^* Therefore, the 
destruction of circulating lymphocytes by ECIB 
or ECIL results lymphocyte depletion of lym- 
phoreticular organs. ^'^^ The relative lymphocyte 
depletion of various areas of spleen and lymph 
