Specific Immunity Flashcards
What makes an immune response specific
A specific immune response is specific because they recognise antigens but have a different response dependent on antigen.
What is an antigen and what can they be
Antigen is something recognised as non self and stimulates immune response.
Can be toxin, protein on cell surface with characteristic shape
What is primary immune response
Primary immune response follows 1st exposure to antigen, lag phase occurs in which no antibody is produced but activated B cells are differentiating into plasma cells.
How are T helper cells activated
T helper cells are activated by bacteria/virus with antigens, the bacterium are engulfed by macrophages, macrophage present antigens on surface and become antigen presenting cell (APC), APC binds to T helper cell with complementary CD4 receptor, T helper cell becomes activated and divides. Divides into active T helper cells and T memory cells.
How are B cells activated
B cells are activated when inactive B cell binds to antigen. Detect antigen with surface receptors. There is a complementary fit between B cell and antigen. This B cell becomes APC. Activated T helper cell with complementary receptor binds to APC and produces cytokines that stimulate B cell to divide. B cells divide to give B memory and B effector cells. B effector cells differentiate into plasma cells. Plasma cells secrete antibodies (needed to destroy pathogen)
When do T killer cells get involved
T killer cells get involved when bacterium or virus infects a body cell.
Bacterium infects a cell of host. Cell presents antigen and becomes APC. T killer cells with complementary receptor binds to APC. T killer cells divide to form 2 clones: active and memory. Cytokines from T helper cells stimulate differentiate. Active T killer cells bind to infected cells presenting antigen. T killer cells releases chemicals which causes pores to form in infected cells, causing lysis
What is structure of antibody
Antibody structure is 4 polypeptide chains held by disulphide bonds. Have antigen binding site. Amino acid sequence and hence shape of binding site is different in each type of antibody which makes antibody complementary to antigen
What is opsonisation
Opsonisation is when antibodies bind to antigens, marking them for phagocytosis
How do antibodies destroy pathogens
Antibodies destroy pathogens by:
Opsonisation
Agglutination
Neutralisation
What is agglutination
Agglutination is action of antibody when it cross links multiple antigens which binds pathogens together, preventing their movement so they are less able to infect body cells.
Clumps of pathogens are easier for phagocytes to ingest.
