A terminally differentiated, post-mitotic, antibody secreting cell of the B cell lineage with the phenotype CD138-positive, surface immunonoglobulin-negative, and MHC Class II-negative. Plasma cells are oval or round with extensive rough endoplasmic reticulum, a well-developed Golgi apparatus, and a round nucleus having a characteristic cartwheel heterochromatin pattern and are devoted to producing large amounts of immunoglobulin.