[The application of CytoDiff for the differential diagnosis of reactive and tumor lymphocytosis.]

CytoDiff reagent was developed to optimize the performance of a WBC differential evaluation. It determines the main population of white blood cells by the expression of linear markers. One of the additional possibilities of using CytoDiff is the differential diagnosis of reactive and tumor lymphocytosis. We studied peripheral blood samples of 76 patients of the All-Russian Central Research Center A.M. Nikiforova EMERCOM of Russia with absolute lymphocytosis of more than 3,0x10⁹/l. The control group included 26 practically healthy people. All performed a clinical blood test on a 5Diff hematology analyzer with smear microscopy, and determination of leukocyte populations by phenotype using CytoDiff. Reference intervals were determined for subpopulations of lymphocytes using CytoDiff. An algorithm has been developed for evaluating the results obtained when determining leukocyte populations by phenotype using CytoDiff for differential diagnosis of reactive and tumor lymphoproliferation. To detect B-cell lymphoproliferative diseases, the use of a cut-off value of 13% or more of the number of leukocytes is optimal. At low values of the relative number of B-lymphocytes, it is important to take into account the results of microscopy of blood smears. If atypical mononuclear cells are absent in smears, then additional clinical and laboratory studies are necessary to establish the cause of lymphocytosis, including phenotyping of peripheral blood lymphocytes to exclude T-cell lymphoproliferative diseases. The expediency of using the CytoDiff reagent for the differential diagnosis of the reactive and tumor nature of lymphocytosis is shown. Already at the stage of primary screening studies, the use of CytoDiff makes it possible to efficiently collect blood samples from patients with possible lymphoproliferative diseases, which significantly reduces the time required for a diagnostic search.