Background Vitamin D is widely recognized as a hormone that is important for calcium homeostasis and maintenance of skeletal health. Vitamin D also plays a role in the function of the immune system. The effect of vitamin D on the immune system is an enhancement of innate immunity coupled with multifaceted regulation of adaptive immunity (Adorini, 2008). In recent years, the discovery of the vitamin D receptor (VDR) in the cells of the immune system and the fact that several of these cells produce vitamin D hormone suggested that it could have immunoregulatory properties. Therefore, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] the biologically active exerts immunomodulation via the nuclear VDR expressed in antigen-presenting cells and activated T/B cells (Sigmundsdottir et al., 2007).

Objectives We evaluated whether there are changes in the serum Vitamin D level in ankylosing spondylitis patients and We related these changes in the level of Vitamin D to the disease activity.

Methods In the current study the whole study population was 40 volunteers divided into two groups; “Target population” and “Control group”. The target population included, 20 ankylosing spondylitis patients from those attending the outpatient clinic and inpatients of rheumatology department, Al-Azhar university hospital. The regional ethical committee of Al-Azhar university Hospitals approved this study. All subjects gave their informed consent for participation. The Control group included 20 healthy volunters. The target population and Control group were subjected to the following evaluation, Routine laboratory investigations, E.S.R., Serum vitamin D (1, 25) level during rest and activity stat serum was measured by radioimmunoassay. Serum calcium (total and ionized), HLA B27. phosphorus, Parathormone,. Plain X-ray of spine, Sacroiliac and hip joints were done. The disease activity was assessed using BASDAI.

Results Level of vitamin D in ankylosing spondylitis patients was statistically significantly lower than those in control group (P>0.001). There was a significant negative correlation between the Levels of vitamin D and disease activity (P>0.001).

Conclusions This study provides further support that Vitamin D is an important immunomodulatory factor involved in autoimmune rheumatic diseases. vitamin D deficiency occurs at a higher rate in patients with autoimmune disorders such as A.S. Routine screening for vitamin D level must be done early in rheumatic diseases and adequate vitamin D intake is recommended.

1. Adorini A., Penna G. (2008): control of autoimmune diseases by the vitamin D endocrine system. Nat Clin Pract Rheumatol. 4: 404-12.

2. Sigmundsdottir H, pan J, Debes GF, et al (2007): DCs metalolize sunlight vitamin D₃ to “program” T cell attraction to the epidermal chmokine CCL 27. Nat Immunol. 8: 285-93

Disclosure of Interest None Declared