Primary biliary cholangitis (PBC) is an immune-mediated chronic cholestasis. The disruption of T cell homeostasis plays an important role in PBC pathogenesis. Lysosomal associated membrane protein 2 isoform A (LAMP-2A) has been implicated in the regulation of CD4⁺ T cell responses, therefore we aim to evaluate the activation state of CD4⁺ T cells in PBC, and to investigate the role of LAMP-2A in it. The peripheral blood of PBC patients (PBC, n=42) and healthy controls (HC, n=20) were phenotypically analyzed, and LAMP-2A expression in CD4⁺ T cells was assessed by flow cytometry. Naïve CD4⁺ T cells of PBC patients were isolated and activated in vitro to estimate their activation responses. Additionally, we assessed the changes induced by silencing LAMP-2A expression. We found that CD4⁺ T cells of PBC patients exhibited significant hyperactivity, and naïve CD4⁺ T cells showed high LAMP-2A expression, which could be a novel biomarker for PBC activity. Moreover, by interfering with LAMP-2A expression in vitro, the overreactions of PBC naïve CD4⁺ T cells were reversed. Our study will help to clarify that increased LAMP-2A expression in the naïve CD4⁺ T cells of PBC patients may lead to a tendency for increased activation responses, which may be involved in the development and progression of PBC. To reverse the hyperactivity of CD4⁺ T cells and reduce the resulting biliary injury, LAMP-2A could be a novel therapeutic target for the treatment of PBC.