The Development of Primary and Secondary Immune Responses to an Antigen

MICROORGANISMS AND DISEASES
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The Development of Primary and Secondary Immune Responses to an Antigen
Primary immune responses occur when antigens are exposed for the first time; some antibodies normally appear in the blood at this stage. Secondary immune responses take place when the antigens are exposed for the second time. It is usually characterized by a shorter lag time when compared to primary responses. B-cells and T-cells develop when the pathogens first activate them.
The immune system consists of biological structures that protect an organism from pathogens. The immune system only functions to detect a wide range of disease-causing microorganisms from bacteria to viruses and differentiate them from the organism's healthy tissues. Abs formed during the secondary response, comes from the memory B-cells and is normally differentiated into secondary plasma cells.
The cells are activated and will continue to stay in their host for the rest of the lifetime. The cells which are activated during the primary exposure would remain the main source of Ag if the repertoire of Abs that respond to the Ag remained static, which implies that the Abs are seen many years would be somehow identical to the Abs seen in the earlier years (Goins et al., 2010). This situation presents a great disadvantage to the host since the pathogens continue to evolve as time goes by.
Grafting of Human Tissues
The grafting of human organs or tissues from one individual to another is called transplantation. The success of the grafted tissues largely depends on the immune system of the host. There are cases where grafting can be performed, but the grafted tissues are rejected by the host's immune system.
Rejection is caused by proteins that change from one individual to another. Such proteins are called alloantigen. The alloantigen is regarded as a foreign matter by the recipient.
MHC molecules are highly polymorphic molecules; they normally trigger a response when nucleated cells are grafted. If the donor's MHC molecules are properly matched with that of the recipient, then the success rate of grafting increases. Perfect matching occurs when the donor and the recipient are related (Janeway et al., 2001). So, it could be that Jack, whose grafting was successful, was related to the donor of the tissue.
Skin can be successfully grafted between different sites on the same individual. One major cause of graft rejection is the response of the antibodies. After transplantation, the alloantibodies that existed in the blood group and the polymorphic MHC can result in rapid rejection of the transplanted organs, a possible explanation as to why Jill rejected the grafted skin (Janeway et al., 2001). In medical terms, it is indicated as hyperacute rejection. If the recipient has antibodies circulating in the body, such antibodies can lead to the rejection of vascularized grafts because they react with the antigens.
Although Jill rejected the grafted skin, clinical therapies could provide a solution to organ failure. Advances in technology made it possible to perform a clinical surgery with much precision minimizing the chances of organ failure (Janeway et al., 2001). Secondly, powerful immunosuppre...