VALUE OF NEUTROPHIL CD16 EXPRESSION FOR DETECTION OF LEFT SHIFT AND ACUTE-PHASE RESPONSE

Fc gamma RIII (CD16) expression of neutrophil granulocytes was measure d in 156 patients by means of fluorescence-labeled antibodies with a f low cytometer. Results were compared with (1) 400-cell manual differen tial count; (2) left shift flagging on hematology analyzers; (3) absol ute neutrophil count; and (4) acute-phase protein levels. Asynchrony w as noted between neutrophil CD16 expression and microscopically define d neutrophil stage, particularly in heavily left-shifted samples, whic h made it impossible to reliably enumerate immature neutrophils on the basis of CD16 expression. According to receiver operating characteris tics, the absolute count of CD16-negative neutrophils was highly discr iminatory for detection of left shift, with an area under the curve (A UG) of 0.842+/-0.03 (SE) and maximum efficiency of 81%+/-3%, but absol ute neutrophil count was not significantly inferior (0.821+/-0.03 and 76%+/-3%). STKS and SE9000 flagging demonstrated efficiency of 76%+/-3 % and 81%+/-3%, respectively. For detection of acute-phase response, a bsolute neutrophil count (AUG, 0.836+/-0.04; maximum efficiency, 80%+/ -4%) outperformed both quantitative neutrophil CD16 expression (0.760/-0.05; 75%+/-4%) and absolute CD16-negative neutrophil count (0.757+/ -0.05; 71%+/-4%); absolute band count performed similarly (0.853+/-0.0 4; 79%+/-4%) and showed high efficiency at high sensitivity and specif icity. Efficiency of analyzer flagging for detection of acute-phase re sponse was not superior to absolute neutrophil count (STKS, 77%+/-4%; SE9000, 78%+/-4%). In conclusion, the diagnostic value of measuring ne utrophil CD16 expression was generally similar to that of less complic ated analytes.