Immune response in hemodialysis patients: is there any difference when lowand high iPTH levels are compared?

Background:Chronic renal failure is frequently associated with secondary hy perparathyroidism and immunological disorders. Recent studies support the h ypothesis that high levels of parathyroid hormone (PTH) may contribute to t he impairment of the cellular and humoral immune response by an immunosuppr essive effect on T- and B-cell functions. However, many studies indicate th at excess PTH exerts a stimulatory effect on T lymphocytes. Since reports a bout the immunomodulatory effect of PTH are controversial, our aim was to c ompare the effect of low and high levels of intact PTH (iPTH) in hemodialys is patients. Methods: The study was performed on 14 hemodialysis patients w ith high levels of iPTP (GI), 12 patients with low levels of iPTH (GII) and 13 volunteers (GIII), for whom time of dialysis, iPTH, total number of lym phocytes, B, CD4(+), CD8(+), lymphoproliferative response to phytohemagglut in (PHA), pokeweed mitogen (PWM) and candidin, IgG and IgM production in vi tro in response to PWM, and interleukin (IL)-2 and IL-6 production in vitro in response to PHA were determined. Results: Patients with high iPTH level s had significantly higher responses to PHA than patients with low iPTH. Ly mphocyte transformation by PWM and candidin antigen was similar in both gro ups of patients, but significantly decreased when compared to controls. CD4 (+) cell counts were significantly increased in GI, and there was a positiv e correlation between the lymphoproliferative response to PHA and iPTH leve ls and CD4(+) number. Conclusion: The present study suggests that high leve ls of IPTH in hemodialysis patients affect T-cell function, increasing the lymphoproliferative response to PHA and the CD4(+) number.