The question is what exactly is the mechanism of action of B lymphocytes sides? How exactly do B lymphocytes engage pathogens? And how exactly do B lymphocytes protect and defend the cells of our body from these pathogenic invasions? So let's begin by discussing what the structure of a B lymphocyte is. So here we have a B lymphocyte and notice that the B lymphocyte contains these receptors on its membrane and they're known as B cell receptors. So let's suppose we have a pathogen that makes their way into our body and that pathogen one way or another will release antigens.