Circulating Follicular Helper T Cells are Decreased in Chronic Lung Allograft Dysfunction.

PURPOSE: Humoral immunity is a fundamental element of chronic lung allograft dysfunction (CLAD) as shown by the presence of B cells and lymphoid follicles in the lung allograft. The formation of lymphoid follicles is under control of follicular helper T (TFH) cells, which also help B cells to differentiate into high-affinity alloantibody-producing plasma cells and memory B cells. The presence and role of circulating TFH cells in CLAD has not yet been investigated and is therefore the objective of our cross-sectional study. METHODS: Whole blood samples were collected from healthy controls (HC) (n=7) and lung transplant recipients (n=31: stable n=12, CLAD n=19). After peripheral blood mononuclear cell isolation, quantification of CD3+ T cells, CD4+ T helper (TH) cells and CXCR5+PD1+ TFH cells was performed using flow cytometry (LSR Fortessa, BD Bioscience). One-way ANOVA with multiple comparisons was used for statistical analysis. RESULTS: No differences were found in CD3+ T lymphocytes between groups, but percentages of CD4+ TH cells within the T cell population were decreased in CLAD versus HC (p=0.005) and the same trend was seen in stable patients versus HC (p=0.07). The number of TFH cells within the TH cells was lower in HC (p=0.044) and in CLAD patients (p<0.0001) versus stable transplant patients. CONCLUSION: Circulating TFH cells are measurable in blood of lung transplant recipients by flow cytometry and are significantly decreased in patients with CLAD compared to stable lung transplant patients. TFH may play a role in immune activation after lung transplantation, however, further investigation is needed.

Publication year:2020