The effect of particulate material on the regulation of chemokine receptor expression in leukocytes

Cellular chemotaxis is one of the most significant components of the host response to implanted materials. However, the effect of materials and their particulates on the regulation of chemokine receptor expression is not well known. This study investigated the effects of alloy particulates on the regulation of CXCR1 and CXCR2 expression on leukocytes from whole blood and purified leukocyte cultures. The volumetric particle concentration and opsonisation dependent manner of CXCR1 and CXCR2 expression on neutrophils and CCR1 and CCR2 expression on monocytes/macrophages was analysed using both flow cytometry (FACS) and real time-PCR. Variation in volumetric concentrations of particulates demonstrated that cell:particulate ratios of 1:1 of non-opsonised NiCr alloy induced the down regulation of CXCR1, and 1:0.25 of opsonised NiCr induced the up regulation of CXCR2. CoCr alloy particulates had no effect on CXCR expression. This study demonstrated that the regulation of chemokine receptor expression could be effected by the properties of materials and the expression of these receptors may contribute to host cellular reactions such as chemotaxis. This study also demonstrated that the response of leukocytes can be demonstrated using a whole blood assay for the study of chemokine receptor expression after direct contact with materials.