ABSTRACT Objective 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. Methods 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. Results 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. Conclusion 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.
Ölçüoğlu et al. (2026) studied this question.