[Antibody-dependent cytotoxicity of blood lymphocytes during rheumatoid polyarthritis].

Lymphocyte dependent-antibody cytotoxicity (LDAC) was studied in 29 patients with rheumatoid arthritis (RA) and 22 controls. A significant increase of cytotoxic index has been noted in RA patients (p less than 0.0001) whatever the ratio effector-target cells could be. There is a correlation between cytotoxic activity and so called "rheumatoid rosettes" (RR) level. This cytotoxic activity is linked to EA rosette forming cells without T cell markers or surface immunoglobulins, as shown by fractionation experiments. EA rosette forming cell depletion is followed by the disappearance of RR and a very important decrease of cytotoxic index. Cytotoxic activity is abolished after RR forming cell depletion while EA rosette level is nearly unmodified. RR forming cells belong to Fc receptor bearing lymphoïd population. They take place in EA rosette forming cell population. Increase of cytotoxicity in RA seems to be directly linked to these so called RR forming cells.