SSB (La protein) is a small RNA binding protein that functions primarily in RNA polymerase III transcript maturation and protection. The protein binds to the 3' poly(U) terminus of nascent tRNA and other small RNA transcripts, protecting them from exonuclease degradation and facilitating proper RNA folding and maturation 12. Beyond its classical role in tRNA processing, SSB also participates in viral translation regulation, specifically binding to the internal ribosome entry site (IRES) of Coxsackievirus B3 and stimulating IRES-mediated translation 3. Clinically, SSB is a major autoantigen in primary Sjögren's syndrome (pSS), a systemic autoimmune disease affecting salivary and lacrimal glands. Anti-La/SSB autoantibodies are detected with high frequency (58-86%) in anti-La/SSB positive pSS patients and are significantly associated with disease manifestations including longer disease duration, parotid gland enlargement, and non-exocrine complications 4. The autoimmune response against SSB is HLA-restricted, notably associated with HLA-DQ heterodimers (particularly HLA-DQA1*0501/DQB1*0201), suggesting that HLA-restricted presentation of SSB peptide epitopes is crucial for triggering the autoimmune response 4. These findings establish SSB as both a functionally important RNA-binding protein and a clinically significant autoimmune target in systemic autoimmunity.