Neutrophil CD64 as a marker for postoperative infection: a pilot study.

The aim of this pilot study was to evaluate the clinical utility of quantitative CD64 measurements to differentiate between systemic inflammation in response to surgical trauma and postoperative bacterial infection. In a consecutive series of 153 patients undergoing elective vascular surgery, peripheral venous blood samples were taken preoperatively on admission and postoperatively during the first 24h. The samples were analysed for C-reactive protein (CRP), total leucocyte counts (white blood cell (WBC)), serum procalcitonin (PCT) and neutrophil CD64 expression. Of the 153 patients, the focus is on those with (1) postoperative infection alone (group 1; n=1 4); (2) pre- and postoperative infection (group 2; n=6); and (3) postoperative fever with no other signs of infection (group 3; n=29). In group 1, all four markers were significantly increased in the 24h after surgery: CD64 (p=0.001), CRP (p=0.001), WBC (p=0.002) and PCT (p=0.012); in group 2, there was no significant difference in the CD64 (p=0.116), WBC (p=0.249) and PCT (p=0.138) values, whereas a marginal significance was shown for CRP (p=0.046); and the results for group 3 were similar to those of group 1. This pilot study suggests that the role of neutrophil CD64 measurements in facilitating the diagnosis of early postoperative infection merits further investigation.

Evaluation of a method for monoclonal antibody HLA-B27 analysis with the CELL-DYN Sapphire haematology analyser.

Analysis of HLA-B27 is usually performed by flow cytometry using commercial single or two colour fluorescence reagents. The CELL-DYN Sapphire (CD-Sapphire) is a high-volume routine haematology analyser that allows cell population analysis by monoclonal antibody fluorochromes analogous to flow cytometry. In this study, in-house flow cytometry analysis (n = 96, HLA-B27, One Lambda) performed on routine patient samples was used as the comparison method for analysis of HLA-B27, One Lambda (n = 40) and HLA-B27/HLA-B7, Immunotech (n = 96) reagents on the CD-Sapphire. The One Lambda results agreed 100% with the comparison method and offered clear population discrimination. The Immunotech combination also had a high level of agreement, but interpretation was more complex because of the wider cross-reactivity of the ABC-m3 antibody with B7 and other HLA-B alleles. When analysing HLA-B27 with antibodies showing nonspecific reactivity, a cut-off staining level yielding high specificity should be chosen, as the primary diagnostic value of HLA-B27 is as a 'rule-out' test for ankylosing spondylitis. The CD-Sapphire incorporates automated sampling and lysis, and medical scientists familiar with the instrument would require little additional technical training to perform the analysis. The reduced preanalytical work and total turnaround time constitute an important step towards automation of HLA-B27 and similar simple high-volume flow cytometry analysis.