Lecture 1: Cellular and Innate Immunity Flashcards
What kind of cell is this?
Where is it located?
What are its functions?
From which cell type is it derived?
Cellular or innate immunity?
Macrophages are large, mononuclear phagocytic cells
Location: in most tissues
Functions: phagocytosis, antigen presentation
Derived from blood monocytes (2-6% of WBCs)
Innate immunity
What kind of cell is this?
Where is it located?
What are its functions?
Cellular or innate immunity?
Neutrophils (polymorphonuclear neutrophilic leukocytes) are phagocytic cells
They comprise 50-60% of WBCs (most abundant WBC)
Function: bactericidal; enter infected tissues to engulf and kill extracellular pathogens
Innate immunity
What kind of cell is this?
Where is it located?
What are its functions?
Cellular or innate immunity?
Eosinophils (1-4% of WBCs)
Function: kill Ab-coated parasites that are too large for phagocyte digestion; also allergic responses
Innate immunity
Top and bottom:
What kind of cell is this?
Where is it located?
What are its functions?
Cellular or innate immunity?
What are similarities and differences between these 2 cell types?
Top: Basophils (0.5-1% of WBCs)
Location: blood
Function: antiparasitic (esp. helminths), allergic responses
Bottom: Mast cells
Location: connective tissues
Function: antiparasitic (esp. helminths), allergic responses
Innate immunity
Same function, different location and cellular structure
What kind of cell is this?
Where is it located?
What are its functions?
Cellular or innate immunity?
Natural killer (NK) cell
* kills some virus-infected cells and some tumor cells
Innate immunity
What type of cell is this?
What are its functions?
Is this involved in cellular and/or innate immunity?
Dendritic cells (DC)
Functions: Antigen uptake in peripheral sites, Ag-presentation to T cells
* bridge innate and adaptive immune responses
Which specialized cells function in allergic responses? What about anti-parasite responses?
Anti-parasitic and allergic responses
* Mast cells (CT): histamine release
* Basophils (0.5-1% WBC) (blood): histamine release
* Eosinophils (1-4% WBC): kill parasites that phagocytes cannot ingest; secretions (ex. toxic to helminths), allergic responses
Which is the most abundant WBC?
Neutrophil (50-60% WBC): polymorphonuclear neutrophilic leukocytes
Function: phagocytosis
Which specialized cells participate in phagocytosis?
Phagocytosis
Neutrophils (50-60% WBC) (polymorphonuclear neutrophilic leukocytes)
* antibacterial function
* enter infected tissues
* engulf/kill extracellular pathogens
Macrophages (from monocytes)
* large, mononuclear
* in most tissues
* Ag presentation
What kind of cell is this?
Where is it located?
What are its functions?
Cellular or innate immunity?
Lymphocytes (25-40% WBC)
in the blood
~20% B cells, 80% T cells
Humoral immunity: Ag-specific Ab produced by activated B cells (plasma cells)
Cell-mediated immunity (CMI): Ag-specific T cell responses
What is clonal selection?
Clonal selection results in the expansion of Ag-specific B and T cell clones.
A single progenitor cell produces many lymphocytes, each with a different specificity.
Clonal selection then removes self-reactive immature lymphocytes (clonal deletion).
This results in a pool of mature naive lymphocytes.
Proliferation and differentiation then produce effector cells and memory cells (T and B cells).
polyclonal response
Antibody responses are polyclonal.
A single antigen may have several epitopes (Ag-recognition sites) which recruit different antibodies.
What are the primary lymphoid organs (adults)? What happens there?
Primary Lymphoid Organs (Where the cells originate/begin development)
* Bone marrow (B cells)
* Thymus (T cells)
These are sites of lymphocyte development and where Ag-specific receptor is acquired
What are the secondary lymphoid organs (adults)?
When do cells migrate to the secondary lymphoid organs?
What happens there?
Secondary lymphoid organs
* adenoid
* tonsil
* lymph nodes
* spleen
* Peyer’s patches
Function: lymphocytes encounter/respond to Ag
- Many mature B and T cells migrate from bone marrow and thymus through blood to secondary lymphoid tissues
- These sites trap Ag and facilitate Ag contact with lymphocytes
- Ag recognition by lymphocytes –> proliferation/differentiation of B and T cells: immune response
Do you have B and T cells with Ag-specific receptors for tetanus? SARS?
Yes – Ag recognition is not pathogen exposure-dependent