Reduced 25-OH vitamin D in patients with autoimmune cytopenias, clinical correlations and literature review

• Vitamin D is reduced and its receptor increased in autoimmune cytopenias.
• Vitamin D deficiency is associated with AIHA and ITP severity at onset.
• Low Vitamin D levels are associated with increased relapse rate in AIHA.
• Vitamin D inhibits anti-erythrocyte autoantibodies production in vitro

Vitamin D deficiency is widespread in Western Countries and has been found related to autoimmune and hematologic disease incidence and clinical course. We evaluated vitamin D levels, vitamin D receptor (VDR) and T helper (Th)1, Th2 and Th17 immunomodulatory cytokines in patients with immune thrombocytopenic purpura (ITP, N = 44), primary autoimmune hemolytic anemia (AIHA, n = 35), Evans' syndrome (n = 5) and chronic idiopathic neutropenia (CIN, n = 19) and also tested vitamin D effect on the in vitro production of anti-erythrocyte autoantibodies. 25-OH-vitamin D levels were significantly lower and vitamin D receptor higher in patients than in controls. Among ITP cases, those with very low vitamin D levels displayed reduced platelet counts, irrespective of the bleeding history. In AIHA patients, LDH values negatively correlated with vitamin D levels in mixed forms, and reticulocyte counts were positively related with vitamin D. Considering treatment, AIHA patients who had been treated with 2 therapy lines or more showed lower mean 25-OH-vitamin D levels than those untreated or treated with one line of therapy only. IL-6, IL-10, IL-17 and IFN-γ levels were higher in patients versus controls, whereas TNF-α was significantly reduced. Finally, vitamin D at concentrations of 10, 20, and 40 ng/mL reduced the in vitro production of anti-erythrocyte autoantibodies both in pokeweed-stimulated and unstimulated cultures. In conclusion, vitamin D is reduced in autoimmune cytopenias and correlate with disease severity, supporting its possible protective role against the development of autoimmunity. Literature review showed vitamin D deficiency reports both in onco- and in non onco-hematologic diseases with a relationship with disease severity/activity in myeloid and lymphoid neoplasms, as well as in sickle cell disease. Supplementation has produced weak results in autoimmune and hematologic diseases, and further studies are needed.