Neutrophil CD64 Is a Good Indicator of Infection and Sepsis.

Sepsis is among the top 10 causes of death, but improvements in the diagnostic tests for detecting and monitoring sepsis and infection have been limited in the last years. Neutrophil CD64 expression increases rapidly in the presence of inflammation mediators and in response to infection and tissue damage. We have evaluated changes in the expression of neutrophil CD64 in infected patients in comparison with other markers of infection and sepsis.

Prospective analysis of 56 blood samples from patients from the intensive care unit at our institution was performed for neutrophil CD64 expression, C-reactive protein (CRP), automated absolute neuthophil count (ANC), and complete manual leucocyte formula including % of bands (BANDS), and % of metamyelocytes and myelocytes (IG). Neutrophil CD64 expression was measured by flow cytometry using a quantitative method (Leuko64^TM, Trillium Diagnostics, LLC). Patients were categorized into 5 groups (CLINIC) based on the clinical history and the degree of a systemic inflammatory response, from 1 (no inflammation) to 5 (septic shock). Statistics were performed using linear regression, correlation coefficient, and Passing-Bablock (P-B) regression. Sensitivity (S), specificity (SP), efficiency (E), and positive and negative predictive values (PPV and NPV respectively) were analyzed for all the parameters measured.

Our results showed a correlation with CLINIC of 0.417, 0.552, 0.268, and 0.136 for CD64, CRP, BANDS, and ANC, respectively. P-B regression was only good for CD64, with a slope of 1.03 (0.6-1.4). Percentages (%) of S, SP, E, PPV, and NPV for CD64 were of 81%, 72%, 71%, 46% and 92%, respectively for groups 4 and 5. For CRP, S was of 93% with SP of 20%, E of 38%, PPV of 27%, and NPV of 91%. The remaining parameters showed deficient correlation with CLINIC. Correlations between CD64 and CRP, BANDS, and ANC were of 0.435, 0.342, and 0.01, respectively.

Neutrophil CD64 expression quantitation provides improved diagnostic detection of infection/sepsis compared with the standard diagnostic tests used in current medical practice. CD64 expression showed a better PPV than CRP, and an acceptable NPV. CRP showed deficient SP and E. BANDS, GI, and ANC showed no correlation with CLINIC. CD64 is a new indicator of infection that deserves consideration to be introduced in the daily hematology laboratory analysis.

No relevant conflicts of interest to declare.