CHAPTER 11 



NONLEUKEMIC LYMPHOCYTOSIS 

 Diseases and Mechanisms 



JOHN B. MIALE 



Qualitative and quantitative changes in the lymphocytes of the peripheral 

 blood are important in recognizing diseases accompanied by specific or non- 

 specific lymphocytic reactions. 



DEFINITION AND SIGNIFICANCE OF LYMPHOCYTOSIS 



Regardless of the nature and etiology of the disorder, it is important first 

 to define the term "lymphocytosis." Lymphocytosis, as are other leukocytoses, 

 is classified as either relative, absolute, or a combination of the two. Relative 

 lymphocytosis is a relative increase in the percentile proportion of lympho- 

 cytes to other leukocytes in the peripheral blood as determined by the 

 differential count. Absolute lymphocytosis, on the other hand, is defined as 

 an increase in the absolute number of circulating lymphocytes and is 

 determined by multiplying the percentage of lymphocytes from the differ- 

 ential count by the leukocyte count per cubic millimeter of blood. Since 

 relative percentile counts express only the ratio between the various leuko- 

 cytes in peripheral blood, it is obvious that relative lymphocytosis may or 

 may not have any significance. Thus, when relative lymphocytosis is due to 

 a decrease in other cells, particularly the neutrophils, the important change 

 is the neutropenia rather than the apparent increase in the lymphocytes. 

 On the other hand, when a relative lymphocytosis is also accompanied by a 

 higher than normal leukocyte count, the relative lymphocytosis is an ex- 

 pression of the increased number of circulating lymphocytes and becomes 

 significant. Unless, then, the total leukocyte count is known, it is difficult 

 to attach any importance to relative values alone. 



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