The immune response - Coursework Example

The macrophages engulf the pathogen entering the body and with the help of the major histocompatibility complex (MHC) combine with the receptors on the T Cells. The type of pathogen entering the body depends as to where it would be taken by the antigen presenting cells. If it belongs to the group of viruses it would be presented to the CD-8 positive cytotoxic cell whereas if it is a microbe it would be presented to the CD-4 positive helper cells. The T Cells also have to be activated with the help of the lymphokines which are released by both the macrophages and t helper cells.

The helper T cells produce lymphokines which further activate the inactive t helper cells and convert them to memory t cells which would be helpful in interacting with the pathogen on the second response. These lymphokines also help to enhance the MHC proteins on the antigen presenting cells and convert the immunological response into a broad spectrum of events. It is then that the T cells function by either delaying the reactions of hypersensitivity or by killing the infected cells of the body (Hall & Guyton 2011; Levinson 2008).

B Cell Response B cells constitute an important part of the humoral immunity by secreting antibodies against the antigens. The response of B cells to antigen is kind of different as the b cells themselves do not act upon the antigens. The B cells react by forming a complex with the antigens. They form similar B cells which are then converted into plasma cells. These plasma cells produce antibodies which can then act upon the antigens. These B cells also produce memory cells like the T cells which can act like quickly upon second exposure to the antigen.

These antibodies can then perform different functions and deactivate the pathogens. Agglutination is one function of the antibodies through which they can destroy the pathogen (Ganong 2005; Levinson 2008). Passive Immunity Passive immunity is the type of resistance which one forms through antibodies which are preformed in another host. These antibodies are administered for certain types of bacteria and viruses. In some cases it is seen that passive immunity is also transferred naturally through fetus to the child and through breast feeding to the child.

The advantage of passive immunity is that it helps to administer antibodies promptly whenever required, however the effects of antibodies are only limited and may last for a certain time (Levinson 2008; Kumar et al 2005). Active Immunity Active immunity is the type of resistance produced after contact with foreign antigens. This involves the usage of vaccines in the human body which allows exposure to a dead organism. This dead organism then helps to produce antibodies against the organism. In this case the immune system responds with a wide production of white blood cells and thus it is more helpful in preventing diseases.

As the memory cells are formed in this type of immunity it is helpful in long term to prevent diseases. One disadvantage of active immunity is that the onset of the immunity is slow as compared to the passive immunity. It is because of this reason that in certain cases Passive-active immunity is preferred in which both the antibodies and vaccines are injected (Guyton & Hall 2011; Levinson 2008). Primary and Secondary Response Human body encounters the foreign antigens through different mechanisms.

When a foreign antigen first enters the body the immune response is quite slow. The