lacks_plasma_membrane_part has plasma membrane part develops from output of memory B cell unswitched memory B cell class switched memory B cell A class switched memory B cell is a memory B cell that has undergone Ig class switching and therefore is IgM-negative on the cell surface. These cells are CD27-positive and have either IgG, IgE, or IgA on the cell surface. class switched memory B lymphocyte Per DSD: Class switched memory B cells are also reportedly CD48-positive, CD229-positive, and CD352-positive. class switched memory B-cell class switched memory B-lymphocyte isotype switching IgM immunoglobulin complex CD27 molecule