Side effects of TNF neutralisation - mostly infectious complications - were recognized, the most important being pulmonary tuberculosis infections. gamma/ d T cells contribute to protective immune response against mycobacterium tuberculosis.
The aim of the present study was to assess the expansion capacity of Vgamma9/Vdelta2 T cells from (tuberculin purified protein derivative (PPD) positive and PPD negative) patients with active rheumatoid arthritis (RA), and to examine the in vitro effect of infliximab on this lymphocyte subset.
28 PPD negative RA patients were studied and compared with 14 PPD positive RA patients, 45 PPD-negative and 110 PPD-positive healthy volunteers. Cell separation, expansion in vitro of Vgamma9/Vdelta2 T lymphocytes (EF) and the expression of tumor necrosis factor receptor II and IFN-gamma content by Vgamma9/Vdelta2 T lymphocytes were studied before and after infliximab in vitro addiction.
The EF from PPD positive subjects was higher than that from PPD negatives. Patients with RA have the highest levels. The addition of infliximab to the cultures from PPD-positive patients determined a significant inhibition of cell expansion and TNF RII expression and a significant decrease of IFN gamma content.
In this study we have documented that gamma/ delta T lymphocytes from patients with PPD positive rheumatoid arthritis have a high capacity to respond in vitro to phosphoantingens with expansion TNF-RII expression and IFN gamma production that is inhibited by the exposure to infliximab. These results might be of relevance in view of the effect of TNF blocking on the pulmonary tuberculosis infection.