The effects of cobalt-chromium-molybdenum wear debris in vitro on serum cytokine profiles and T cell repertoire.

Cobalt-chromium-molybdenum (CoCrMo) alloy-based metal-on-metal prostheses have been the implant of choice for total hip replacement in younger patients. However 6.2% of patients require revision of their CoCrMo total hip replacement (THR) implant within five years of surgery and their use was restricted in 2013. We aimed to determine if there were individual differences in the immune response to wear debris that might indicate a poor outcome with a CoCrMo prosthesis. Blood from 22 donors was incubated with CoCrMo particles (>99.9% less than 10 μm diameter) generated by a wear simulator for 24 h. T cell phenotype was assessed by immunostaining and secretion of 8 different pro- and anti-inflammatory cytokines was measured using multiplex technology. Clear differences were seen between individuals in the induction of Th17 and Th1 responses, with some donors showing pro-inflammatory responses (increased IL17 or IFNγ) and others showing anti-inflammatory responses (decreased IL17 or IFNγ). The only differences seen for gender and age related to increased IL-10 expression from T cells in females (p = 0.008) and a trend towards decreased IL-6 expression systemically for older donors (p = 0.058). We conclude that individuals show differential responses to CoCrMo wear debris and that these responses could give early indications of the suitability of the patient for a metal-on-metal prosthesis.