CHAPTER 15: IMMUNITY INTRO Flashcards
specific immunity/adaptive
- third line of defense
- ACQUIRED immunity using B and T cell lymphocytes
what is an antigen
a molecule that stimulate a response by T and B cells
2 parts of Specific Immunity
Specificity: make antibodies that work against specific antigens of that bacteria/virus
Memory: lymphocytes “remember” first encounter w antigen and respond fast in future infections w that same antigen
1st step: cell receptors identify the microorganisms/antigen
- how?
- receptor of lymphocyte attach to nonself/foreign molecules
- recognize self molecules, and send signals to other cells in the system to come and help elicit immune response
2 Classes of Receptors
MHC I: on all cells but RBC, all nucleated body cells
MHC II: on certain WBC (B and T)
Lymphocyte Receptors: B and T
BCR: bind free antigens directly
TCR: cannot bind directly, needs MHC to present antigen TO the T cell (MHC peptide complex)
Clonal Selection Theory
lymphocytes use 500 genes to make specific receptors
- we use VDJ recomb to create unique antigen receptors
clonal selection…
- undifferentiated lymphocytes divide and change randomly to create even more unique receptor specificity
Lymphocyte Development
Bone marrow: differentiate into B or T, B stays here
Thymus: is where T cells go
Why does lymphatic tissue not penetrate bone marrow and thymus?
- the cells are not mature here, they cannot be exposed to the immune system
- when mature, T and B will migrate to secondary lymphoid tissue
Lymphocyte Specificity process
- in genetic makeup the antigen enters teh system
- each clone (Diff type of WBC) express a single specificity and then waits to use it
Clonal Selection Steps
introduce each type of antigen into the immune system to create a generally distinct lymphocyte
- then causes it to create clones of that cell so it can react to that antigen
(clone lots of the WBC that can fight that SPECIFIC antigen)
