Cells of inflammation and Immunity
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Transcript Cells of inflammation and Immunity
Cells of inflammation and
Immunity
G. Wharfe
2005
Immune system
Detect and respond to antigens
Protects against pathogenic microorganisms
Also elicits response against noninfectious foreign
organisms
Used in inflammatory response and tissue repair
Immune response
Response needs to be quick and efficient
Two systems
– Innate
– Adaptive
Cells of IR
All derived from BM stem cells
Influenced by growth factors
Begin as multipotent stem cell
Develop into committed stem cells
Innate immune system
First to respond
Limits infection before adaptive response
Usually involve nonlymphoid cells
Cells are macrophages and polymorphonuclear
neutrophils(PMN)
Also involves complement and acute phase
proteins
If innate immunity cures infection-no adaptive
immunity develops
Normal haematopoiesis
Adaptive immunity
Inducible antigen specific response
Primary lymphoid organs produce
lymphocytes capable of responding to
various antigens
Lymphocytes form naïve pool in blood
Lymphocytes circulate in peripheral
lymphoid organs
Location for Ag-dependent IR
Immunoglobulin
Cells of innate immune system
All are bone marrow derived
Lineage commitment depends on stromal
contact and cytokines
Dendritic cells-Antigen presenting cells
Develop from peripheral blood monocyte
precursors
Found in the interstitium and T cell areas
Stimulate Ag specific T cells
Phagocytic cells
PMN’s
Macrophages
Granulocytes
Inflammatory cells
Contain cytoplasmic granules
Neutrophils
Eosinophils
Basophils
Neutrophil
Stages of granulocyte maturation
Neutrophils
Major phagocytic granulocyte
Contain multilobed nucleus
Neutrophilic granules
Respond to chemotactic stimuli
Activated by macrophage and endothelial
derived cytokines
Major cell of acute inflammation
Primary effector cells in IR to pyogens
Neutrophils
Have Fc receptors for IgG and c’
Bind and phagocytose opsonised antigens
Link between 2 arms of immune system
Regulates activation and recruitment of
macrophages by cytokines
Phagocytosis
Principal mechanism of pathogens
Enter site of infection
Opsonins produced to allow phagocytosis
Taken into vacuole
Killing by aerobic or anaerobic mechanisms
Cytokine induction
Phagocytosis
Eosinophil
Eosinophils
Contain eosinophilic granules
Express Fc receptors for IgE
IgE prevalent in parasitic infections
IgE mediates activation of eosinophil killing
mechanisms
Role in immediate hypersensitivity to
allergens
Cause tissue injury and inflammation
Basophil
Basophils
In circulation –basophils
In tissue- Mast cells
Express Fc receptors for IgE
Release chemical mediators of immediate
hypersensitivity
Monocyte
Macrophages
Main cells of chronic IR
Regulators of specific acquired response
Fewer numbers than neutrophils
Peaks in hours to days
Participate in both acute and chronic
inflammation
Phagocytose apoptotic PMN’s
Tissue macrophages
Second major class of phagocytic cells
Provide innate immunity and initiate host
defenses
Release inflammatory cytokines
Act as APC
Link between innate immunity and acquired
humoral and cellular immunity
Cells of monocyte macrophage
system
Lymphocytes
B lymphocyte
T lymphocyte
NK lymphocyte
Lymphocyte
Lymphocytes
Mediate adaptive immune response
Recognize antigen specifically
Each clone has antigen specificity
Arrange V, J and D elements if Ig and T cell
receptor genes to form different clones
B lymphocytes recognize native Ag
T lymphocytes recognize processed Ag
Lymphocytes
Ag binds to receptor
Lymphoid activation and Clonal expansion
Effector cells or products all have same
specificity as parent cell
Inactivation of self reactive clones
Lymphocytes
Ag independent maturation occurs in primary
lymphoid organs
Ag dependent occurs in secondary lymphoid
organs
Cells are indistinguishable morphologically
Phenotypically and functionally different
B lymphocyte development
B lymphocytes
Generate Ab response
Formed with other white cells in BM
Ab neutralize pathogens, opsonize
pathogens, activate complement
Act as APC for T cells
Generate memory B cells
Plasma cell
Plasma cells
Not usually found in PB
Responsible for Ig production
T lymphocyte development
T cells
Generate CMI
Directly by differentiating into cytotoxic T
cells
Indirectly by activating macrophages
Help B lymphocytes
Develop from BM progenitors which migrate
to thymus
CD4 and CD8
T cell functions
Delayed hypersensitivity
Cell mediated immunity
Graft rejection
Contact allergic reactions
Cytotoxic responses to other cells
Facilitate Ab production by B cells
Memory T cells
Lymphoid organs
Interaction of lymphocyte with virus
NK cells
Also known as LGL
Target virus infected cells
Target tumor cells
Have receptors for IgG
Mediate ADCC
Immune response
Differences between cells of innate
immunity and lymphocytes
Different ways of recognizing
microorganisms
Direct
Indirect
Specific Ag recognition
Cytokines
Molecules secreted by cells(lymphocytes)
and which affect the function of other cells
Secreted in response to specific stimulus
Interleukin is a type of cytokine
Role of interleukins