Serum 25-Hydroxyvitamin D Level Is Not Related to Regulatory T Cells or Kidney Function in Renal Transplant Recipients

Abstract

Background: Vitamin D and regulatory T cells (Tregs) are both involved in promoting peripheral tolerance and limiting chronic inflammatory diseases. Renal transplant recipients (RTRs) are likely to have low vitamin D levels, which may influence their immune status.

Aim: The aim of our study was to assess the usefulness of serum 25-hydroxyvitamin D (25(OH)D) and Tregs in estimation of the protolerogenic milieu in RTRs within 1 year after kidney transplantation.

Methods: 26 RTRs (15M/11F, aged 49.1 ± 15.4 years) 3 to 13 months after kidney transplantation and 24 healthy volunteers were enrolled for the study. The serum level of 25(OH)D was measured with ELISA and peripheral blood immune cell populations (T lymphocytes, helper T lymphocytes, and Tregs) were assessed by flow cytometry.

Results: Severe 25(OH)D deficiency (<10 ng/mL) was found in one RTR (3%) and moderate deficiency (<20 ng/mL) in 12 (46%), while vitamin D sufficiency was found in 6 patients (23%). The RTRs did not differ from the control group in observed 25(OH)D levels. None of the cell populations were related to the level of 25(OH)D in the control group. In RTRs, there was a negative association between 25(OH)D and total T lymphocyte count (r_s = -0.45, P = .023), but 25(OH)D was not related to any other cell population or kidney function.

Conclusion: The results of our study suggest that serum 25(OH)D is not sufficiently reflective of vitamin D status to apply this measure in assessment of protolerogenic milieu in RTRs.