[Temperature-dependent pseudoleukocytopenia and in vitro studies on the underlying mechanism]

Spuriously low electronic white-cell count was obtained on EDTA-anticoagulated blood from a 54-year-old male suffering from liver cell carcinoma. In an attempt to understand better the phenomenon, in vitro studies were performed. The blood smear anticoagulated with EDTA revealed remarkable agglutinations of leukocytes, mainly neutrophils but not lymphocytes. The EDTA-treated blood showed maximal leukocytes-agglutinations at room temperature but no agglutination at 37 degrees C. The agglutinated leukocytes, moreover, were dispersed by incubating the blood at 37 degrees C. Although agglutination occurred in some degree in the blood anticoagulated with Na-heparin or Na3-citrate, it was much less pronounced compared to the EDTA-treated blood. Remarkable leukocytes-agglutinations were induced when EDTA-anticoagulated blood from healthy donor was mixed with serum from the patient at room temperature. These results suggest that the phenomenon of in vitro leukocyte agglutination and consequent pseudoleukocytopenia is due to leukocyte agglutinin in serum from the patient. The mechanisms were discussed comparing with pseudothrombocytopenia caused by platelet agglutinin.