In cases of immune-mediated arthritis in joints, what cell type is typically observed?

• A. Eosinophils
• B. Lymphocytes
• C. Neutrophils
• D. Basophils

Answer: (B)

Immune-mediated arthritis is driven by adaptive immune responses targeting joint components, so the synovial tissue is typically infiltrated by lymphocytes. T cells and B cells (with plasma cells) invade the joint, reflecting a chronic autoimmune process and ongoing antibody-mediated activity against joint antigens. Eosinophils and basophils are not characteristic in this context, and neutrophils are more commonly associated with acute or septic processes rather than the classic immune-mediated pattern. While neutrophils can appear during flares, the predominant cell type you’d expect in immune-mediated joint inflammation is lymphocytes, which is why this choice is the best fit.