Factors that determine Responsiveness of an Individual against Antigen (Lab Report Sample)

5. Enumerate the factors that determine responsiveness of an individual against an antigen
* Specificity and diversity immune responses are specific for distinct antigens
* Memory exposure of the immune system to a foreign antigen enhances its ability to respond again to that antigen. Rsponses to second and subsequent exposures to the same antigen called secondary immune responses are usually more rapid larger and often qualitatively different from the first exposure.
* Clonal expansion lymphocytes undergo considerable proliferation following exposure to antigen
* Contraction and homeostasis after exposure to antigen
* Nonreactivity to self one of the most remarkable properties of every normal individual’s immune system is its ability to recognize respond to and eliminate many foreign (nonself) antigens while not reacting harmful he did that individuals own (self) antigenic substancess
6. Differentiate the various types of antigen and give examples for each:
* According to relation to the host
* Autologous antigens are found within the same individual they are not foreign to that individual
* A skin graft from an individual's thigh to his chest is an autograft, and is not foreign
* Syngeneic antigens are found in genetically identical individuals.
* Individuals from an inbred strain of mice of identical twins an inbred strain is a syngeneic graft or an isograft, and is not foreign
* Allogeneic antigens (alloantigens) are found in genetically dissimilar members of the same species
* A kidney transplant from mother to daughter is called an allograft or a homograft, and it is foreign
* Xenogeneic (heterogenic) antigens are found in different species and have several particular characteristics
* A transplant of monkey kidney to humans is called a heterograft or xenografts, and it is foreign
* Heterophile antigens are heterantigens that exist in unrelated plants or animals but are either identical or closely related in structure so that antibody to one will cross-react with antigen of the other.
* Human blood group A and B antigens, which are related to bacterial polysaccharides.
* B. According to how antigen are found in the body:
* Sequestered antigens- antibodies are not ordinarily made to Autologous brain or cornea protein because these substances do not come in contact with antibody-producing cells since they are inaccessible to antibody-forming lymphoid tissues
* The central nervous system and cornea are devoid of lymphatics, and the cornea is also nonvascularized; both lymphatics and blood vessels are required for an immune response
* Tissue-specific (organ-specific) antigensvarious organs have in their makeup certain antigens unique to those organs.
* Thyroid has an organ-specific antigen, thyroglobulin
* Tissue-type
* Blood group antigens (histocompatibility) they are examples of alloantigens
* The presence of incompatible blood group antigens may cause haemolytic disease of the newbowrn or the post-transfusion reaction. The success of transplantation of foreign tissues and organs is determined by the histocompatibility antigens.