If a foreign agent enters in to the body, immune system responds in different ways to get rid of it from the body. Response of immune system is not same for all foreign agents.
The response depends on the type of antigen or foreign substances which entered the body.
Responses of immune system to any foreign agent are broadly classified in to two main types one is “Humoral immune response” and the other one is “Cell mediated immune response”.
Even though the aim of both is removal of the foreign agent, the way they work is different and the cells as well as cell components involved in the reaction are different.
Immunoglobulins secreted by activated B cells play a major role in humoral immunity. Binding of antibodies to the pathogen is not sufficient to remove the foreign agent from the body.
However it makes the foreign agent susceptible for further actions of immune system. In cell mediated immunity, cells chiefly T cells and other accessory cells involve directly in immune reactions.
Binding of the immune cell to the target confirms its destruction and removal from body. Cell that is binding to the foreign agent becomes cytotoxic in cell mediated immunity.
Irrespective to the difference in function both humoral and cell mediated immune responses exhibit complex interrelationship to fine-tune immune reactions to almost any antigen, or molecule that stimulates the immune response.