154 The Lymphocyte and Lymphocytic Tissue 



clinical findings are doubtful. In the second place the diagnosis of infections 

 mononucleosis in my opinion must not be made unless three criteria 

 are fulfilled: (1) a compatible clinical picture, (2) a compatible peripheral 

 blood smear, and (3) typical serologic results showing the presence of anti- 

 body not absorbed by Forssman antigen but absorbed by beef erythrocytes. 



Fig. 11-6. Viral hepatitis, peripheral blood. Wright's stain, (x 1700) 



However, it is common experience that sometimes cases are encountered 

 satisfying the first two criteria but not the third. Many have recorded 

 this, 4 - ,; - *• 20 blaming either the specificity of the test or the system of interpre- 

 tation or technical factors. Some have attempted to separate such an entity 

 by the term "pseudomononucleosis." 19 



I have commented previously 14 on a group of 58 cases studied during the 

 winter of 1956 in Miami. During a period of three months, we followed 

 carefully cases of an apparently epidemic disease which clinically had the 

 features of infectious mononucleosis. Serial studies on the peripheral blood 

 showed numerous atypical lymphocytes, seldom below 50 per cent of the leu- 

 kocyte count, cells which could be classified as one or the other of Downey's 

 three types and which we thought morphogically typical of the cells seen 



