The diagnostic value of CD11b expression on peripheral blood neutrophils for detection of spontaneous bacterial peritonitis

Background: Spontaneous bacterial peritonitis (SBP) is associated with the highest mortality among end-stage cirrhotic liver disease patients. Neutrophil CD11b expression increases on the neutrophil surface within 5 min of exposure to bacteria. Paracentesis remains the only accepted method for accurate evaluation of patients, with many drawbacks; hence, a diagnostic noninvasive marker with a very high sensitivity and high diagnostic accuracy is very necessary. Aim of the study: to evaluate the neutrophil CD11b as a non-invasive biomarker for the diagnosis of SBP, comparing its sensitivity and specificity to other traditional methods. Patients and Methods: 200 patients who had liver cirrhosis with ascites were recruited to the Hepatology department inpatient wards of the National Liver Institute, Menoufia University. They were divided into Group I: 100 patients with SBP and Group II: 100 patients with non SBP ascites. All studied patients were subjected to full clinical examination, abdominal ultrasound, paracentesis, and laboratory investigations including ascetic fluid (AF) examinations. The CD11b expression and its mean fluorescence intensity (MFI) were assessed on peripheral blood neutrophils by flowcytometry. Results: There was a significant increase in the MFI of CD11b in the SBP group compared to the non SBP group. At cut off >20 for MFI of CD11b with a sensitivity of 100% and specificity of 100% can discriminate between SBP and non SBP cases followed by ascetic fluid TLC examination at a cut off 0.26 (×103) with a sensitivity of 92%, and specificity of 96%, then, AF neutrophil count at cut off 0.25 (×103) with a sensitivity of 80%, specificity of 100%, and AF culture examination with a sensitivity of 56% and specificity of 100%. Conclusion: The measurement of CD11b MFI on peripheral blood neutrophils is a useful non-invasive marker with high sensitivity and specificity to predict SBP compared with other methods. Further large-scale studies are needed to study the value of CD11b MFI level in the SBP follow-up therapy.