[Expression and diagnostic value of lymphocyte subsets and activation status in non-Hodgkin's lymphoma-associated hemophagocytic lymphohistiocytosis].

<b>Objective:</b> To determine the expression and diagnostic value of peripheral blood lymphocytes and functional activation status in non-Hodgkin lymphoma with hemophagocytic lymphohistiocytosis (NHL-HLH) . <b>Methods:</b> We retrospectively analyzed clinical data from 30 newly diagnosed NHL-HLH patients admitted to Jiangsu Province Hospital from September 2022 to September 2023. We assessed peripheral blood lymphocytes and activation status by flow cytometry. Forty newly diagnosed patients with NHL who received treatment at our hospital during the same period and had lymphocyte and functional activation indexes were selected as the control group. The differences in relative and absolute lymphocyte counts and functional activation indexes between the two groups were compared. The optimal cutoff values for continuous variables were calculated from the receiver operating characteristic curve and logistic regression analysis was used to evaluate the risk factors in NHL patients with HLH. <b>Results:</b> A total of 30 NHL-HLH patients were evaluated, including 12 T-cell lymphoma and 18 B-cell lymphoma patients. Forty individuals were in the control group, which included 19 T-cell lymphoma and 21 B-cell lymphoma patients. The absolute counts of CD3(+) T, CD4(+) T, CD8(+) T, and NK cells, along with the relative count of NK cells, were significantly lower in the HLH group compared with that in the control group (all <i>P</i> values<0.01) . The expression of CD38 and HLA-DR on CD8(+) T-cell activated subgroups was significantly higher in the NHL-HLH group compared with that in the control group (CD8(+)CD38(+)/CD8(+) T expression median: 57.4% <i>vs</i> 21.5%, <i>P</i><0.001; CD8(+)CD38(+)/CD8(+) T expression median: 49.7% <i>vs</i> 33.5%, <i>P</i>=0.028, respectively) . In addition, CD28 expression on CD4(+) and CD8(+) T cells was significantly higher in NHL-HLH patients (<i>P</i><0.01) . ROC curve and multivariate logistic regression analyses revealed that absolute NK cell count ≤72.0 cells/μl, CD4(+)CD28(+)/CD4(+) T >94.2%, and CD8(+)CD28(+)/CD8(+) T >38.4% were risk factors for predicting the occurrence of NHL-HLH patients. The sensitivity and specificity of the regression model were 86.7% and 86.1%, respectively, with an area under the curve of 0.94 (<i>P</i><0.001) . <b>Conclusions:</b> In NHL patients with HLH, there was a significant reduction in the absolute number of peripheral blood lymphocyte subpopulations, whereas T-cell function was notably activated. Specifically, absolute counts of NK cells ≤72.0 cells/μl, CD4(+)CD28(+)/CD4(+) T >94.2%, and CD8(+)CD28(+)/CD8(+) T >38.4% were identified as risk factors for predicting the development of NHL-HLH patients. This will assist in early clinical diagnosis and treatment.