CD4 and primary biliary cholangitis: T lymphocytes, especially CD4+ T cells, have been implicated in the development of sarcoidosis (45) and other diseases such as gastrointestinal diseases (e.g., celiac disease, IBD), endocrine diseases (e.g., T1DM), liver diseases (e.g., primary biliary cholangitis), neurological diseases (e.g., multiple sclerosis), and cutaneous diseases (e.g., psoriasis) (46–48).