What 2 cell types do hematopoietic stem cells from the bone marrow differentiate into?
Myeloid progenitor cells and lymphoid progenitor cells
What do myeloid progenitor cells differentiate into
Innate immune cells - monocytes - macrophages and dendritic cells
What do lymphoid progenitor cells differentiate into (adaptive and innate)
Adaptive immune cells - T & B lymphocytes
Innate immune cells - Natural killer cells
Innate vs adaptive immunity (what they detect, how are receptors generated/encoded, repeat exposure response strength)
Innate - detects common microbial structures, receptors encoded in germline, same response upon repeat exposure
Adaptive - detects vast repertoire of molecules, receptors generated by somatic recombination, improved response upon repeat exposure
What 4 antigen types do B cells recognize
Proteins, lipopolysaccharides, lipids, nucleic acids
Which antigen type do T cells recognize
Peptides derived from proteins
Adaptive immunity mediated by B cells against extracellular microbes using antibodies to neutralize and eliminate microbes/microbial toxins
Humoral immunity
Adaptive immunity mediated by T cells against intracellular microbes by killing infected host cells
Cellular immunity
5 phases of adaptive immune response (recognition, activation, effector phase, decline, memory
Recognition - naive lymphocyte recognizes corresponding antigen
Activation - lymphocytes differentiate and begin clonal expansion
Effector phase - differentiated lymphocytes eliminate microbes
Decline - after microbial elimination, the signal for activation disappears, and most of the activated cells die by apoptosis
Memory - some remaining memory lymphocytes survive for months or years
Two signals required for lymphocyte activation
Antigen receptor binding to antigen, and microbial/innate immune signal
Why are subsequent responses to a microbe stronger
Increased number of B cells after first exposure leads to stronger subsequent responses, memory cells initiate a more rapid response
T/F: Each B/T cell expresses a unique BCR/TCR
True
Where are BCRs of a naive B cell located
The BCRs are restricted to the plasma membrane of the B cell
Activation of B cells results in
Clonal expansion, differentiation into antibody secreting B cells (BCRs secreted as antibodies)
Antibodies target ___ microbes
Extracellular
Where do APCs present the antigens to T cells
Peripheral lymphoid tissues
Co-receptor for cytolytic vs helper T cells
Tc - CD8 Th - CD4
Class II MHCs are found on ___, while Class I MHCs are found on ___
Professional APCs (dendritic, macrophages, B cells), all nucleated cells
CD4 helper T cell function
Detect antigens presented by professional APCs (Class II MHC) and secrete cytokines to activate other components of the immune response (macrophages, B cell antibody secretion)
CD8 cytolytic T cell function
Detect microbial antigens presented by all nucleated cells (Class I MHC) and destroy the presenting cell
What cells are found in the lymph node cortex
B cells (location of germinal centers)
What cells are found in the lymph node paracortex
T cells and dendritic cells
Process of lymphocyte activation in the lymphatic system
Lymphocytes enter lymph nodes and are activated by APCs that enter from peripheral tissue - lymphocytes exit lymph nodes into circulation to inflamed tissue where they mediate microbial destruction
