IgA , sIgA- common in secretions such as saliva and bile. Unable to cross the placenta due to size. IgE - not common. Found on surface of mast cells. Specific Cellular Immunity .
Lymphocytes are immune system cells that have large round nuclei.
Functionally there are two main subtypes of lymphocytes- T and B cells. The T cells are functionally important for fighting cancer, and in protection from fungi, Mycobacterium spp., and viruses. The B cells produce antibody, and are called plasma cells when they do so. Interaction between T and B cells is important in immunity, as is interaction between macrophages and lymphocytes. These cells secrete molecules that kill target cells, principally by punching holes in the target cell membrane.