neutrophil

• 60-65% of WBC
• granulocyte; leukocyte - 3-lobed nucleus with pink granular cytoplasm
• phagocytic: during infection, migrates from the blood to tissues where phagocytoses pathogen then dies and forms pus
• does not present antigens
• part of innate immune response

eosinophil

• very few in WBC - function mainly in tissues
• granulocyte (bright orange granules); leukocyte
• defends against internal parasites

basophil

• few in WBC
• granulocyte (deep purple); leukocyte

monocyte

• 5-10% of WBC
• mononuclear; leukocyte
• mobile progenitors of macrophages; travel in blood to tissues where mature into macrophages

lymphocyte

• 25-30% of WBC
• monocyte; leukocyte

white blood cells (WBC);

• includes neutrophils, eosinophils, basophils, monocytes, lymphocytes
• derived from hematopoietic stem cells

any organism with the potential to cause disease

• bacteria
• viruses
• fungi
• internal parasites

• skin (epithelial): made of tough, keratinized cells; breached by physical damage
• mucosal surfaces: covered in mucus which contains glycoproteins, and enzymes to protect from damage and infection; i.e. lysozyme in saliva
• acidic environment in skin, stomach, and vagina

causes inflammation at site of infection 

1. pathogen recognition: includes soluble proteins, and cell-surface receptors
2. recruitment of effector mechanisms: kill and eliminate pathogens; effector cells and complement

soluble proteins that act as triggers for cells

• induce local dialation of blood capillaries (vasodilation)
• change adhesive properties of vascular endothelium: easier for WBC to enter tissue from bloodstream (infiltration)

highly specialized defense against a specific pathogen

• cell-surface receptors are highly specialized
• long-term immunological memory: faster, stronger response on next exposure (acquired or protective immunity)

memory cells within the body that allow a stronger, faster adaptive immune response to a pathogen; usually due to prior exposure to the same pathogen;

immunological memory

 macrophage

• phagocytic cell: dispose of dead cells as well as foreign invaders
• professional antigen presenting cells
• 5% of blood cells
• resident in tissues
• express MHC class II
• part of both innate and adaptive immune responses
• secrete cytokines

 dendritic cell

• monocyte; leukocyte; phagocytic
• distinctive star shape
• act as cellular messengers for adaptive immune response
• reside in tissues but bring/present antigens to T cells

 mast cell

• monocyte; granulocyte (contain histamine); leukocyte
• reside in tissue
• major contributor to inflammation and allergies
• histamine released within 5-10 min of contact with antigen
• contributes to anaphalaxis

natural killer (NK) cell

• large granular lymphocytes
• part of innate immunity
• kill virus-infected cells; secrete cytokines
• no specific antigen receptor

• antigen receptors are immunoglobulins

• engulfment and destruction of particulate material; i.e. bacteria
• neutrophils, macrophages, dendritic cells
• mechanisms of killing: acid; anti-microbial peptides ("defensins"), superoxides/hydrogen peroxide, nitric oxide, proteolytic enzymes

1. antigen binds to cell receptors (can be antibody mediated/F_c receptors)
2. engulfment: membrane surrounds and fuses around antigen forming a membrane-bound vesicle (phagosome)
3. degradation: vesicle fuses with lysosome, containing destructive materials (see 'mechanisms of killing' above) to form phagolysosome - some intracellular bacteria prevent this phase and infect the cell instead

• antigen receptors are T-cell receptors (TCRs)

where lymphocytes develop and mature;

include the bone marrow and thymus

• bone marrow: where B-cells develop and mature; where T-cells develop
• thymus: where T-cells mature

white blood cells

• large: natural killer cells (innate); granular cytoplasm
• small: B cells, T cells (adaptive); little to no cytoplasm - mature lymphocytes travel through the blood, secondary lymphoid tissues, and lymphatics, then back to the blood (recirculation) but the majority are in the the lymphoid organs and tissues

• all other lymphoid tissue except bone marrow and thymus - includes spleen, adenoids, tonsils, appendix, lymph nodes, and Peyer's patches (in the gut)
• where mature lymphocytes are activated
• connected (except for the spleen) to the lymphatic vessels which drain the extracellular fluid and return it to the blood (lymphatics)
• provide signals that keep circulating lymphocytes alive

• lymph arrives from afferent lymphatic vessels and leaves via the efferent lymphatic vessel
• lymph is filtered by macrophages as it travels through the node
• dendritic cells take up residence in the T-cell areas
• circulating small lymphocytes from the blood and lymph enter the node - become activated through interactions with dendritic cells and each other

• effector B cells
• make and secrete antibody
• either stay in lymph node or migrate to bone marrow

• effector T cell that kills infected cells

• effector T cells

• effector T-cells

formation of blood cells

• all blood cells from hematopoietic stemm cell (HSC) in bone marrow
• programmed set of steps
• when HSC proliferates it forms a "progenitor cell" and a new HSC

adult stem cell transplantation

• Restores ability to make WBC in individuals w/o HSC

1. remove bone marrow and freeze
2. hi dose chemotherapy to destroy HSC
3. return HSC removed earlier

• soluble form of immunoglobulin
• the constant region has binding sites for cell-surface receptors (F_c receptors) on phagocytes, complement, and other cells

• red pulp filters the blood: (innate response)
  • removes damaged/old red blood cells
  • macrophages filter out infectious agents like blood borne bacteria (even non-opsonized ones)
• white pulp: site of lymphocyte activation to antigens in the blood (adaptive response)
• part of the secondary lymphoid tissue
• connected only via blood

• uses whole blood sample
• counts # of cells in known volume and calculates concentration in WBC/microliter
• normal = 5,000-10,000 WBC/microliter

• uses blood smear prepared with Wright's Stain and 100x microscope with oil immersion
• count 100 WBC
• find percentage of each WBC type: normally
  • neutrophils: 60-65%
  • monocytes: 5-10%
  • lymphocytes: 25-30%
  • eosinophils: few
  • basophils: few

• total WBC x %
• calculates the amount of each WBC type (WBC/microliter)

cancer of the WBC;

results in elevated WBC count = 100,000/microliter

increase in neutrophils;

usually also increased WBC count

with bands:

there are immature neutrophils which means an ongoing disease process

removal of the spleen:

• done for trauma or hematologic diseases
• more susceptible to serious infections with bacteria that replicate in the blood stream

• mostly the B-cell area
• where germinal centers are located
• helper T-cells move here to stimulate the differentiation of B-cells into plasma cells (migrate to the medulla)

• the T-cell area
• macrophages filter the lymph
• dendritic cells move in to interact with circulating T-cells

• the central part of the lymph node
• plasma cells migrate here and secrete antibody
• drains to efferent lymphatic vessel and blood

• formed from two polypeptides: heavy and light chains (2 identical copies of each)
• have a variable region and constant region (both heavy and light chains)
  • variable region: binds antigen
  • constant region: indentical from one Ig to another - in membrane-bound Ig the heavy chain constant region connects to the transmembrane region that anchors the Ig

• consists of αlpha and beta chains anchored to the membrane
• each chain has a variable and constant region

• occurs in activated dividing B cells;
• introduces nucleotide substitutions into the immunoglobulin heavy- and light- chain genes;
• introduces varying antigen affinities and results in strengthening of antibody affinity during adaptive response

some of the pattern recognition receptors (PRRs) which allow the cells of the innate immune system to detect and respond to pathogens

• 10 different kinds: capable of recognizing microbial nucleic acids and invariant molecules chracteristic of different pathogens (i.e. bacteria, fungi, viruses, and parasites)
• signaling receptors that enhance antimicrobial activity and secretion of cytokines; induce the maturation and migration of dentritic cells
• share a signalling pathway with IL-1 receptor