Abatacept acts as a co-stimulation modulator preventing activation of T cells. Although it is approved for the treatment of rheumatoid arthritis (RA), its effects on adaptive immune response have not been fully elucidated.
To observe, in a cohort study, based on a clinical practice setting, the variation of peripheral blood T cells, immunoglobulin levels, and autoantibodies in the serum of RA patients during abatacept therapy.
Our study comprised 48 RA patients treated with abatacept. All clinical data were collected at baseline and after 3 months of treatment. Clinical and laboratory tests included erythrocyte sedimentation rate, C-reactive protein, 28-joint disease activity score, RF, anti-citrullinated protein antibody, total immunoglobulins, immunoglobulin A (IgA), immunoglobulin G (IgG), immunoglobulin M (IgM), and lymphocyte sub-population.
Total immunoglobulin serum levels significantly decreased after 3 months of treatment and correlated positively with disease activity both at baseline and after 3 months of abatacept treatment. A reduction of serum IgM, IgG, IgA and RF was also demonstrated. The absolute number and percentage of cytotoxic (CD8+) T cells significantly decreased after 3 months of abatacept treatment, in particular the percentage of cytotoxic (CD8+) T cells significantly decreased only in patients responding to the treatment.
Our results highlight a different role of abatacept in the modulation of the adaptive immune response in RA by the reduction of polyclonal B-cell activation and cytotoxic T cells.