Immune Imbalance in Sickle Cell Anemia: Flow Cytometric Insights Into Regulatory T Cells and Neutrophil Dynamics

To investigate immunophenotypic alterations in regulatory T cells (Tregs) and neutrophil dynamics in adult sickle cell anemia (SCA) patients during painful crises and steady state.

Ninety-three participants were included: 17 SCA patients in painful crisis, 27 in steady state, and 49 healthy controls. Flow cytometry was used to assess CD3⁺CD4⁺CD25⁺FoxP3⁺ Tregs and related subsets. Hematological parameters were evaluated by complete blood counts. Statistical analyses included group comparisons, multiple regression, and ROC curve analysis.

SCA patients exhibited significant reductions in CD25⁺ and CD4⁺ T cell subsets, despite preserved FoxP3⁺ Treg frequencies. White blood cell and neutrophil counts were elevated, especially during crisis. Neutrophil and lymphocyte percentages significantly predicted T cell subset levels. ROC analysis identified CD3⁺ and CD4⁺ percentages as strong classifiers of disease state.

Despite numerical preservation of FoxP3⁺ Tregs, SCA is marked by impaired T cell activation and sustained innate immune activation. These immune shifts may relate to but do not directly determine end-organ complications. Functional assays and longitudinal studies are needed to elucidate Treg competence, hydroxyurea effects, and age-related immune changes in SCA.