Cells

Question 1

Give relevant histological features, lineage, location, function

Neutrophil

Answer 1

AKA polymorphonuclear leukocyte
Neutral granulocyte
Leukocyte/myeloid/HSC/mesoderm.
Phagocytic. Not antigen-presenting. (Innate response)
Most common leukocyte in peripheral blood and major arbiter of inflammatory rxns/ “first line of defense” (pus!)

Question 2

Give relevant histological features, lineage, location, function

Eosinophil

Answer 2

Bilobed, (basic) granulocyte (at VERY low levels in blood)
Leukocyte/myeloid/hsc/mesoderm
Specialized for parasites; also mediates allergic rxns (Innate response)
Tend to be found in sub epithelial tissue

Question 3

Give relevant histological features, lineage, location, function

Basophil

Answer 3

Basophilic granulocyte
Leukocyte/myeloid/hsc/mesoderm
Circulating leukocyte
Participate in allergic and anti-parasitic responses

Question 4

Give relevant histological features, lineage, location, function

Mast cell

Answer 4

Large, mononuclear, basophilic (acid) granulocyte - histamine
Leukocyte/myeloid/hsc/mesoderm
Facilitates extravasation of WBC’s - mediates vasodilation, increased vascular permeability
Found near vascularized connective tissue
Differentiated by enzymes: Tryptase [mucosa] / Tryptase + chymase [other connective tissues] - both contain histamine, leukotrienes

Question 5

Give relevant histological features, lineage, location, function

Monocyte/Macrophage

Answer 5

Monocyte is circulating precursor to macrophage.
Leukocyte/myeloid/hsc/mesoderm
Phagocytic, antigen presenting (Innate response)
Powerful recruiters of inflammatory response

Question 6

Give relevant histological features, lineage, location, function

Dendritic cells

Answer 6

? / Myeloid/hsc/mesoderm

Phagocytic; by far the most efficient antigen presenting cell (Interfaces btw innate/adaptive immunity)

Question 7

Give relevant histological features, lineage, location, function

Natural Killer cells

Answer 7

Mononuclear granulocyte
Lymphoid / hsc / mesoderm
Cytotoxic cells important for mediating viral response [produce and strongly respond to IFN- (Th1) and IL4/5/10/13 (Th2)]
INNATE - CD56. NO antigen specific receptors; NOT MHC restricted,

Question 8

Give relevant histological features, lineage, location, function

Gamma-delta lymphocytes

Answer 8

Lymphocyte/Lymphoid/HSC/Mesoderm
INNATE
Recognize small molecule phosphoantigens.
Found at host-environmental interfaces (think MALT)
produce inflammatory IL-1, 6, 17

Question 9

Give relevant histological features, lineage, location, function

Natural Killer T lymphocytes

Answer 9

Lymphocyte/Lymphoid/HSC/Mesoderm
Cytotoxic cell carrying an (early?) TCR that is restricted to GLYCOLIPID antigens. Role is probably to provide immediate help to adaptive system (I’ll call them innate since they don’t have the full TCR complement)
Express both NK marker CD56 and TC markers CD3/αβ

Question 10

Give relevant histological features, lineage, location, function

B cell

Answer 10

Lymphocyte/Lymphoid/HSC/Mesoderm

They live to encounter antigen so they can grow up to be plasma cells (with the help of some CD4T’s)

Question 11

Give relevant histological features, lineage, location, function

Plasma cell

Answer 11

Lymphocyte/Lymphoid/HSC/Mesoderm
Terminally differentiated B cells produce highly specific antibody to one antigen epitope - some will evolve to memory cells

Question 12

Give relevant histological features, lineage, location, function

CD8 T cell

Answer 12

Lymphocyte/Lymphoid/HSC/Mesoderm

Cytotoxic T - recognize and kill viral-infected cells

Question 13

Give relevant histological features, lineage, location, function

CD4 T cell

Answer 13

Lymphocyte/Lymphoid/HSC/Mesoderm
Helper T - produce molecules and cytokines that either direct the immune response at an area, mediate the B cell response, or both

Question 14

Give relevant histological features, lineage, location, function

Treg cell

Answer 14

subset of CD4; CD4/CD25. Dependent on FOXP3 expression - CTLA4. May be induced by TGF-β
May be induced in Thymus after interaction with AIRE (nTregs)
…in periphery (iTregs)