Peripheral-type benzodiazepine receptors in human mononuclear cells of patients affected by osteoarthritis, rheumatoid arthritis or psoriasic arthritis

Objectives The objective of this study was to evaluate the kinetic parameters at equilibrium of peripheral benzodiazepine receptors (PBR) in human mononuclear cells from patients affected by osteoarthritis (OA), rheumatoid arthritis (RA) and psoriasic arthritis (PA). Design and methods Mononuclear cells were obtained from 10 patients with OA, 10 patients with RA and 10 patients with PA. Evaluation of kinetic parameters of PBR was performed using [3H]PK 11195, a specific radioligand for this receptor, and compared with 10 healthy controls. Results The results show a statistically significant decrease (37.5%, as an absolute percentage) in the maximal number of binding sites (Bmax) of patients with OA, compared with healthy controls; however, the values of the dissociation constant (Kd) at equilibrium do not show any statistically significant variations. Conclusions These data further confirm the presence of peripheral biochemical alterations in OA. As peripheral benzodiazepine receptors appear to be involved in the immune function, and in the protection of hematopoietic cells against oxygen radical damage, the observed decrease in Bmax might be related to cellular protection.