Objective: To prospectively evaluate histopathologic, blood cellular, serologic, and clinical changes in response to abatacept treatment in patients with primary Sjögren’s syndrome (SS).
Methods: Blood, saliva, and minor salivary gland biopsy samples were obtained before and after the last of 8 doses of abatacept in 11 primary SS patients. The histologic data evaluated the numbers of lymphocytic foci and B and T cell subtypes (CD20+, CD3+, CD4+, and CD8+). The numbers of FoxP3+ regulatory T cells were measured and the FoxP3:CD3 ratio was calculated. Histologic data were compared with results from peripheral blood and with changes in saliva secretion.
Results: The numbers of lymphocytic foci decreased significantly (P = 0.041). Numbers of local FoxP3+ T cells decreased significantly in percentage of total lymphocytic infiltrates (P = 0.037). In the peripheral blood, B cells increased (P = 0.038). This was due to an expansion of the naive B cell pool (P = 0.034). When adjusting for disease duration, an increase was also noted for total lymphocytes (P = 0.044) and for CD4 cells (P = 0.009). Gamma globulins decreased significantly(P = 0.005), but IgG reduction did not reach significance. Adjusted for disease duration, saliva production increased significantly (P = 0.029).
Conclusion: CTLA-4Ig treatment significantly reduces glandular inflammation in primary SS, induces several cellular changes, and increases saliva production. Remarkably, this increase in saliva production is significantly influenced by disease duration.