Cells of Adaptive Immune System
T Lymphocytes
CD4+: produce cytokines
CD8+: lyse infected cells; also called cytotoxic T cells
called helper T cells
B cells (innate)
Plasma cell
produce Ab's
require T helper cell stimulation to switch from making IgM to IgG; IgG is more effective in producing memory cells
APC
Professional APC: DC and Macrophages; these can activate naive T cells
Non Professional APC can present antigen to memory T cell or one that has already seen it's antigen before
Clonal Selection Theory
upon binding antigen, divide and produce clones
cells with a wide range of specificities exist in body
each cell possesses a single specificity
applies only to adaptive immune system
slow
produces memory cells
Cytokines
small proteins that act through a receptor
enhance innate and adaptive immune responses
autocrine, paracrine, endocrine
regulate hematopoiesis
cell survival/proliferation
cell migration & inflammation
characteristics
redundancy
synergy: in the presence of other cytokines, they can be enhanced
pleiotrophy: response varies based on amount
antagonism
Immunopathology
Ineffective Immune response: rare, immunodeficiency; immunodeficiency can lead to infection
overactive immune response; hypersensitivity
Inappropriate response to self; autoimmunity
Infection can suggest an Immunodeficiency Problem; the following deficiencies can cause susceptibility to these pathogens.
T cells: mycobacteria, fungi, parasites, bacteria
Antibodies: encapsulated organisms, viruses
PMN: staphylococcus, serratia, pseudomonas, aspergillis, candida
Complement: Neisseria sp
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Immunodeficiency Can Result From:
latrogenic immunosuppresion
metabolic defects
Immune senescence
malnutrition
malignancies
infectious diseases
trauma, surgery, stress
depression: can cause decreased NK function, increased Ab levels, decrease in IL-2 (T cell proliferation) and IFN gamma (activates macrophages); IL-4 increase Ab levels; decreased DTH response (lack of inflammation to TB test is an example);
Th1
Th2
Intracellular: IL12, IFN-gamma
Extracellular: IL-4, IL-13
When Th1 response predominates, increased response to intracellular pathogens w/ increased delayed hypersensitivty
decreased extracellar response and decreased allergic inflammation
When Th2 response predominates there is decreased intracellular response, decreased DTH, increased extracellular pathogen response and increased allergic inflammation
hypersensitivity response: produces harm not protection
can involve responses to external antigens as well as autoimmunity