The significance of T-follicular helper and T-follicular regulatory cells in autoimmune hemolytic anemia

Background
Autoimmune hemolytic anemia (AIHA) is an acquired autoimmune disease resulting in the production of antibodies directed against the patient’s red blood cells, causing destruction of red blood cells. T-follicular helpers (Tfh) and T-follicular regulatory cells (Tfr) perform opposing actions in regulating germinal center responses. The dysregulation of their actions may ultimately advance the development of autoimmune diseases. There is evidence that patients with autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis, exhibit an imbalance of Tfh and Tfr cells.


Aim
To study the characteristics of Tfh and Tfr cells and analyze the Tfh/Tfr cells ratio in AIHA.


Patients and methods
The study was carried out on 50 patients with AIHA (primary not on treatment) who presented to Assiut University Hospital and 25 healthy age-matched and sex-matched controls. We determined Tfh and Tfr cell expression by flow cytometry using monoclonal antibodies CD3, CD4, CD185, PD1, and Foxp3.


Results
Within the CD3+CD4+ lymphocytes we gated on C-X-C motif chemokine receptor type 5 (CXCR5+) T cells (CD185) and we determined the fraction of PD1+ FOXP3- and PD1+ FOXP3+ from peripheral blood in patients with AIHA to analyze Tfh (CD4+ CXCR5+PD1+ Foxp3-) and Tfr (CD4+CXCR5+PD1+ Foxp3+) cells. There was a statistically significantly higher median expression level of Tfh (CD4+ CXCR5+PD1+ Foxp3-) (26.70 vs. 1.80%), P value less than 0.001, and lower median expression level of Tfr (CD4+CXCR5+PD1+ Foxp3+) cells among cases compared to controls (1.87 vs. 33.30%), P value less than 0.001. There was a statistically significant higher Tfh/Tfr cells ratio among cases compared to controls (15.19 vs. 0.09), P value less than 0.001.


Conclusion
Our results suggested that the increased Tfh cells and decreased Tfr cells may be involved in the immunopathogenesis of AIHA. Tfh/Tfr cells ratio has the most important role in the pathogenesis of AIHA. Our results may provide new insight into the role of Tfh cells as a new cellular target in AIHA treatment.