It is put into blood plasma by the liver and removed by the kidney. This process is called excretion. Your kidneys also excrete excess water and salts from your body. Hydrogen carbonate ions are produced when carbon dioxide produced by tissue respiration is absorbed by blood plasma. In your lungs, hydrogen carbonate ions turn back to carbon dioxide which is excreted when you exhale.
Antibodies kill bacteria.
Antibodies are goodies and bacteria are baddies . If the goodies win, you live to a ripe old age. You may have a natural immunity to some diseases, but other diseases are likely to kill you if you do not receive medical attention. The problem is that the germs multiply faster than you white blood cells kill them. If you cannot make the right antibodies you will get very ill and could die.