Kidneys perform all the functions except
Antibody, also called immunoglobulin, a protective protein produced by the immune system in response to the presence of a foreign substance, called an antigen.
The kidneys remove waste products through blood filtration. They also remove excess water from the body and so help to regulate blood pressure. DCT and collecting duct allow extensive reabsorption of water and certain electrolytes, which help in osmoregulation: H+, K+, and NH3 could be secreted into the filtrate by the tubules to maintain the ionic balance and pH of body fluids.