The antibodies produced by lymphocytes in vertebrates are the type of ______ proteins.

They are protective proteins which protect the body from ill effects of poisonous (toxic) substances and pathogenic invaders (virus, bacteria and other pathogens) by destroying the toxins and invaders. Important defence proteins are antibodies or immuno-globulins produced by lymphocytes in vertebrates. Interferon protects cells from the attack of viruses. Thrombin and fibrinogen form blood clots to prevent loss of blood and infection at sites of injuries. Certain proteins, called exploitive proteins, are normally toxic, but they may play a defensive role under certain conditions.