cells of the immune system
First a little about the types of white blood cells (called leukocytes):
a. macrophages - phagocytic
b. eosinophils - phagocytic
c. neutrophils - phagocytic
d. basophils - release histamine; involved in the inflammatory response.
e. lymphocytes - 3 types: B cells, T cells and Natural Killer cells.
(Be careful not to get the terms leukocyte and lymphocyte confused!)