Antigen-presenting subsets of neutrophils: A diagnostic marker of clinical efficiency of immunomodulatory therapy with synthetic thymic hexapeptide in children with acute hematogenous osteomyelitis

The multiple functions of neutrophilic granulocytes (NG) are associated with various subsets and phenotypes of these cells. Previously, in children with severe purulent inflammatory diseases, a correlation was found between the severity of disease and contents of CD66b + CD16 + CD33 + HLA-DR + NG (APC-NG) subset. Thus, the determination of the APC-NG subset may serve as a valuable diagnostic tool and an efficiency index during complex therapy in severe purulent-inflammatory diseases. Our goal was to assess the dynamic changes in APC-NG levels in children with AHO in comparison with the dynamics of indicators of clinical effectiveness during immunomodulatory therapy with a synthetic thymic hexapeptide (HP). Materials and methods. The study group (SG) included 15 children aged 10-15 years with acute hematogenic osteomyelitis (AHO), the comparison group (CG) consisted of 13 conditionally healthy children. The contents of NG expressing CD66b, CD16, CD33, HLA-DR (FC500, Beckman Coulter), and expression density of these molecules was evaluated in peripheral blood (PB) of patients and controls. The PB samples were collected before surgery, on the 10 th day of therapy, and before discharge. The immunological parameters of control samples were studied once. The amounts of APC-NG were found to be increased by 18 times in study group before treatment, being decreased by 1.9 times on the 10 th day after the beginning of treatment, and by 3.8 times at the time of discharge (20-25 th day). However, the content of APC-NG after treatment did not reach the CG levels. Moreover, a decreased number of APC-NG correlated with positive clinical dynamics: there was an earlier regression of general and local symptoms. A delay in positive changes of APC-NG was observed in the absence of clinical efficiency, thus requiring a revision of therapeutic strategy, and changes of antibacterial therapy. Conclusion: The study demonstrated high clinical efficacy of thymic HP in the complex treatment of children with AHO and a diagnostic potential of the APC-NG contents as a diagnostic marker for monitoring efficacy of postsurgical treatment of pediatric AHO patients. This marker may also serve as a tool that allows for timely correction of AHO treatment at the in- and outpatient stages.