Title: Biology 201 Fundamentals of Biology II
1Biology 201Fundamentals of Biology II
- Rob Mustard
- Adjunct Faculty
PALOMAR COLLEGE
2Leukocytes Immune Response
- Blood cells are one of the fluid Connective
Tissues - Red blood cells (erythrocytes)
- Mammalian RBCs lack nuclei and mitochondria
- 7 ?m diameter
- White blood cells(leukocytes)
- Giemsa stain to differentiate WBCs
6-7 million erythrocytes / ml3 7,000 leukocytes /
ml3
3Immune Response Modes
- Innate Immunity
- Rapid (and general) response to a broad range of
microbial invasion - Acquired (Adaptive) Immunity
- Secondary (and highly-specific) response to
previously-encountered pathogens - Vertebrates have both forms of immune-response
mechanisms
4Innate Immunity
- External defenses include
- Skin impenetrable to most viruses bacteria
- Mucous viscous fluid that traps microbes
- Cellular secretions sebaceous (oil) sweat
glands reduce skins pH to 3-5 lysozyme digests
Gram cell walls - Internal defenses begin after bacteria invade,
typically through a break in skin or other
epidermal layer
5Inflammatory Response
- Tissue damage from physical injury leads to
cascade of chemical signals - Histamine, stored in mast cells in connective
tissue - Nearby capillaries become dilated and leaky,
allowing passage of macrophages and increased
blood flow - Increased local blood supply leads to redness,
heat and swelling (inflammation) - Macrophages move out into damaged tissues, in
interstitial spaces between cells - Nonspecific Inflammatory Response
6Leukocytes Involved in Innate Immunity
Phagocytes
- Neutrophils
- 60-70 of all leukocytes, live only a few days
- Big 12-15 ?m (2x erythrocytes)
- Nucleus has 2-5 lobes (polymorphic)
- Monocytes
- 5 of all leukocytes
- Biggest 20 ?m
- Lighter, frothy horseshoe-shaped nucleus
Neutrophils are granular
Monocytes are agranular
7Leukocytes Involved in Innate Immunity
Phagocytes
- Eosinophils
- Rare in blood smears (2-4)
- Big 12-15 ?m (same size as Neutrophils)
- Nucleus has 2 lobes
- Dendritic Cells
- Patrol interstitial spaces of skin mucosal
membranes - Phagocytize invaders, process present antigen
material (APCs) - Activate acquired immune system
Eosinophils are granular
8Leukocytes Involved in Innate Immunity
Hypersensitivity
- Basophils
- Rarest of the leukocytes (lt0.5)
- 10-12 ?m diameter
- Respond to allergic reactions (e.g., bee wasp
stings, pollen) - Very granular nucleus often obscured
- Live for about 2 weeks
Basophils are very granular
9Leukocytes Involved in Innate Immunity
Cytotoxicity
- Natural Killer Cells
- A specialized lymphocyte
- Attack virus-infected cells
- Attack cancer cells (tumors)
- NK cells recognize infected/defective cells via
surface features - Bind to target cells, release chemicals
(perforins) that lead to apoptosis
An NK cell (N) attached to a "target" cell "T".
The NK cell will kill the now helpless target
cell quickly, by the injection of deadly perforin.
10Leukocytes Involved in Acquired Immunity
- Lymphocytes
- Very common in blood 20-40 of WBCs
- Slightly larger than RBCs (10 ?m)
- Dark-staining, circular nucleus
- Agranular cytoplasm is transparent
11Lymphocyte Specialization
- Vertebrate lymphocytes take on specialized roles
- Circulate through blood lymph, concentrated in
spleen lymph nodes - B T cells bear 100K antigen receptors (all the
same)
Antigen- binding sites
IgM Receptors
V
V
Variable regions
V
Light chain
V
V
V
C
C
C
C
C
C
Constant regions
b chain
? chain
Heavy chains
T cell
B cell
12Acquired Immunity Responses
- Humoral Response
- Dendritic cell (APC) engulfs pathogen, presents
antibody via cell-surface protein (MHC class II) - Helper T cell binds to presented antigen
- APC releases cytokines to stimulate production of
more activated T cells - Activated B cells secrete antibodies, which
immobilize pathogens, marking them for
destruction by macrophages - Cellular Immune Response
- A cell other than a leukocyte takes up and kills
a microbe, presents antigen on surface (MHC class
I) - Cytotoxic (activated) T cell binds to presented
antigen, releases perforins, lyses infected cell
13PALOMAR COLLEGE