Prostate-specific antigen, or PSA, is a protein produced by normal, as well as malignant, cells of the prostate gland. The PSA test measures the level of PSA in a man's blood.

Immunoglobulin E (IgE) is a type of antibody (or immunoglobulin (Ig)"isotype") that has only been found in mammals. IgE is synthesised by plasma cells. IgE's main function is immunity to parasites such as helminths like Schistosoma mansoni, Trichinella spiralis, and Fasciola hepatica. Total IgE is utilized during immune defense against certain protozoan parasites such as Plasmodium falciparum. Total IgE may have evolved as a last line of defense to protect against venoms.