Bone Abstracts

Background: Zoledronic acid (ZA) is associated with a transient post-infusional acute phase reaction (APR) due to the activation of γδTCR lymphocytes (γδTcells).

Aims: To investigate if APR correlates with γδTcell percentage or cytokine polarization, or with 25-OH vitamin D levels; to identify a 25-OH vitamin D level associated with a lower risk of APR.

Methods: Sera for ELISA test (IFNγ, IL17, and IL13) and peripheral blood mononuclear cells for T lymphocyte subpopulation FACS analysis (CD3–FITC, γδTCR-PE, IL23R-Alexa Fluor700, CD27-PE-Cy7, and CD69-PERCP-Cy5.5) were drawn from 52 osteoporosis (OP) patients treated with 5 mg i.v. ZA. A second sample was drawn 1 week later from nine patients (5 APR+).

Results: 26/52 (50%) patients developed APR and had higher percentages of γδTcells (4.6±5.4 vs 3.7±2.3, P=NS) and lower 25-OH vitamin D levels (22.1±8.2 vs 33.2±17 ng/ml, P=0.005). No correlation was found between 25-OH vitamin D and γδTcells subsets. Further, APR was associated with lower percentage of basal γδTcells Th2 (31.6±27.4 vs 33.1±27.9, P=0.022). No differences were found in Th1, Th17, and Th2 cytokine levels before and after the infusion or in relation to APR. No significant differences were found in γδTcells subsets one week after ZA infusion. The patients with 25-OH vitamin D levels >30 ng/ml had a significantly lower risk of APR (OR 8.6, 95% CI 2.3–33.8).

Conclusion: Insufficient 25-OH vitamin D levels are associated with the risk of ZA-associated APR, suggesting that vitamin D supplementation before ZA infusion could prove protective. High percentages of γδTcells Th2 are correlated to a minor risk of APR and may provide helpful marker.