Impact of Major Orthopedic Surgery On Regulatory CD4+ T Lymphocytes and Cytokines in Transfused and Non-Transfused Patients.

In this study, we aimed to investigate regulatory CD4+ T cells induction and cytokine profile in transfused and non-transfused surgical patients.

Thirty-five patients undergoing elective hip replacement were recruited for this study and prospectively evaluated. Blood samples were obtained before surgery (D0) and on days 1 (D1) and 4 (D4) after surgery. Quantification of regulatory T lymphocytes was done by flow cytometry using CD4, CD25, FoxP3, CTLA-4, GITR and CD69, while cytokines (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-17A, TNF-α, IFN-γ and TGF-β) levels were determined by multiplexed immunoassay system.

From the 35 patients recruited for this study, 18 (51.4%) received allogeneic non-leukodepleted red cells transfusion during or after surgery. There were no significant differences in clinical or epidemiological characteristics between transfused and non-transfused groups, except for the duration of surgery, being longer in transfused patients (p<0.001). Results of total lymphocyte count and subsets of CD4+ T cells in the 35 patients are summarized in the table:

The total lymphocyte count was significantly decreased only in transfused patients. No significant difference was seen in the percentage of CD4+CD25highFoxp3+ T lymphocytes by comparing days D0, D1 and D4. However, a significant increase of CD4+CD25-CD69+ cells was observed by comparing D1 vs. D4 [0.61(0.23–2.69) vs. 2.27 (0.64–4.45); p=0.001] in transfused patients, but not in the group of non-transfused patients [0.36(0.31–0.81) vs. 1.02(0.42–1.52); D1 vs. D4. Similarly, we also detected a significant increase in the number of CD4+GITR+ T cells in the group of transfused patients [D1 vs. D4; 3.12±2.01 vs. 5.19±3.33; p=0.007). Total hip replacement also led to substantial increase of the following cytokines: IL-6 (p<0.001, D0 vs. D1 and p<0.001, D0 vs. D4), IL-8 (p<0.001, D0 vs. D1 and p=0.017, D0 vs. D4), IL-10 (p<0.001, D0 vs. D1). However, no differences regarding cytokines levels were seen comparing groups of transfused and non-transfused patients.

This study demonstrated that although allogeneic non-leukodepleted red cells transfusion is associated with decrease of total lymphocyte count following major surgery, there was a significant increase of total CD4+ T lymphocytes with no difference observed in transfused and non-transfused patients. However, a significant increase of CD4+CD25-CD69+ and CD4+GITR+ T lymphocytes was observed in the transfused group on D4, possibly reflecting the late effect of transfusion on induction of these subsets of CD4+ regulatory cells. The increase of pro-inflammatory IL-6, IL-8 and anti-inflammatory IL-10 levels indirectly highlights the imbalance on immune response after surgical trauma. Further studies, with a larger cohort and functional assays, investigating these CD4+ T cells subpopulations following major surgery and the impact of allogeneic non-leukodepleted red cells transfusion on these cells should be addressed.

No relevant conflicts of interest to declare.