Hepatitis C virus (HCV) infects approximately 170 million people worldwide. About 10-50% of persons with HCV have MC. MC is associated with the development of autoimmune symptoms and B cell proliferative disorders. We plan to study B cells from individuals chronically infected with HCV as well as from healthy controls. We sort B cells into different types, and we analyze these types for differential levels of gene expression. We are testing the hypothesis that certain types of B cells from subjects with MC have increased expression of genes that allow for increased cell survival.