**Background of Anti-Keratin Antibodies (AKA):**
Anti-keratin antibodies (AKA), first identified in the 1970s, are autoantibodies targeting cytokeratins, particularly acidic type I keratins (e.g., CK8. CK18) in epithelial tissues. They are primarily associated with rheumatoid arthritis (RA), where their presence correlates with disease severity and erosive joint damage. AKA detection, often via indirect immunofluorescence using rodent esophagus sections, reveals a characteristic "keratin pattern" staining.
While less sensitive than anti-cyclic citrullinated peptide (anti-CCP) antibodies, AKA exhibits high specificity (~95%) for RA, aiding early diagnosis and differential diagnosis from other rheumatic diseases. Their formation is linked to post-translational modifications (e.g., citrullination) of keratin in inflamed synovial tissue, triggering immune responses.
Studies suggest AKA may participate in RA pathogenesis by forming immune complexes that amplify inflammation. Despite being partially eclipsed by anti-CCP in clinical practice, AKA remains a valuable biomarker, especially in seronegative RA cases. Ongoing research explores their role in prognosis and disease monitoring, underscoring their enduring relevance in autoimmune diagnostics.