ab22401

Natural killer cells and g/d T cells in synovial fluid and in peripheral blood of patients with psoriatic arthritis

A. Spadaro¹, R. Scrivo¹, T. Moretti², G. Bernardini², V. Riccieri¹, E. Taccari¹, R. Strom², G. Valesini¹

¹Department of Applied Medical and Clinical Therapy, Division of Rheumatology and ²Department of Cellular Biotechnologies and Haematology, University "La Sapienza", Rome, Italy

ABSTRACT
Objective
NK surface markers and g/d TCR antigen are involved in non-MHC-restricted cytotoxicity, which represents a major effector mechanism of the cell-mediated immune response. We evaluated in PsA patients SF and PB lymphocytes expressing these cellular subsets in order to obtain information on the possible role played by them in the disease.

Methods
We studied 29 PsA and 27 RA patients, as well as 27 healthy controls. In 17 PsA and 16 RA patients with knee joint effusion, analysis of SF was performed. SF and PB lymphocyte analysis was performed by direct dual immunofluorescence flow cytometry using anti-CD3, anti-CD4, anti-CD8, anti-CD19, anti-TCR-g/d-1 and anti-CD16 and anti-CD56 monoclonal antibodies.

Results
PsA and RA patients had, with respect to controls, lower values (both as percentages and in absolute numbers) of PB T cells expressing g/d TCR. SF lymphocytes of PsA and RA patients were characterised, as compared to PB lymphocytes, by lower numbers (both in absolute numbers and in relative terms) of NK and NK-T cells. Considering the absolute numbers of the various lymphocyte subsets, a strong correlation was found in PsA SF between g/d T cells and NK (p < 0.0007) or NK-T cells (p < 0.0003), as well as between NK and NK-T cells (p < 0.0019). There was instead no statistically significant correlation among the different SF or PB lymphocytes and the most relevant clinical or serological parameters.

Conclusion
This study, analyzing the impairment of different subsets involved in non-MHC-restricted cytotoxicity, suggests that this component of the cell-mediated immune response seems to play a pivotal role in the development of PsA.

Key words
Psoriatic arthritis, natural killer cells, g/d T cells.

Please address correspondence and reprint requests to: Prof. Antonio Spadaro, Dipartimento di Clinica e Terapia Medica Applicata, Divisione di Reumatologia, Universitá "La Sapienza", Azienda Policlinico Umberto I, Viale del Policlinico 155, 00161 Roma, Italy.
E-mail: a.spadaro.reuma@virgilio.it.