Applied value of peripheral neutrophile granulocyte CD64 test in the diagnosis of pulmonary infection in patients after renal transplantation

Objective To evaluate the early diagnostic value of CD64 index for bacterial infection and cytomegalovirus (CMV) infection in patients following renal transplantation.Method Seventy-nine recipients who underwent renal allograft transplantation between March 2010 and February 2011 were enrolled in the study.All patients received maintenance immunosuppressive therapy protocol based on tacrolimus.All patients were classified into three groups according to etiology:simple bacterial infection group (n =42),simple active CMV infection group (n =17),and stable function group (n =20).CD64 index and absolute T cells count were analyzed by using flow cytometry.White blood cells (WBC) and neutrophils were measured by using automated hematology analyzer.CMV infection was diagnosed by indirect imrnunofluorescence method.Results The absolute counts of WBC,CD3+ and PMN showed no significant difference among stable function group,bacterial infection group and CMV infection group (P =0.32,0.77 and 0.98,respectively)before transplantation.The WBC counts in bacterial infection group and active CMV infection group were significantly different from those in stable function group (P＜0.001).The WBC counts in active CMV infection group was significantly less than those in bacterial infection group and stable function group,and those in bacterial infection group were significantly more than those in stable function group.The CD3 + counts in bacterial infection group and active CMV infection group were significantly different from stable function group (P =0.019).The CD3+ counts in active CMV infection group were significantly less than those in bacterial infection group and stable function group,and those in bacterial infection group were significantly more than those in stable function group.The PMN counts in bacterial infection group and active CMV infection group were significantly different from control group (P＜0.001).The PMN counts in active CMV infection group were significantly less than those in bacterial infection group and stable function group,and those in bacterial infection group were significantly more than those in stable function group.The levels of neutrophil surface CD64 had no significant difference among active CMV infection group,bacterial infection group and stable function group (P＞0.05) before transplantation.However,the levels of neutrophil surface CD64 in bacterial infection group (4.087 ± 1.485) were significantly higher than those in stable function group (1.031 ± 0.412) after transplantation,there was statistically significant difference between bacterial infection group and active CMV infection group (1.694 ± 0.801) (P＜0.001),and there was no statistically significant difference between acute CMV infection group and stable function group (P＜0.05).The best cutoff value of CD64 index to predict bacterial infection was 1.51,and the sensitivity,specificity and AUC were 95.3％,86.5％ and 0.91 respectively.The best cutoff value of CD64 index to predict active CMV infection was 1.48,and the sensitivity,specificity and AUC were 52.94％,90.0％ and 0.76 respectively.Conclusion CD64 index is of great value for the early diagnosis of bacterial infection and CMV infection in patients after transplantation,and has higher sensitivity,specificity and accuracy. Key words: Kidney transplantation;  CD64;  Infection;  Flow cytometry