Serology Day 1 - Immune system, immunoglobulins, complement Flashcards

1
Q

Antigen

A

Molecule that is capable of eliciting formation of antibodies in an immune competent host

Reacts with antibody or t cell

Not able to evoke IR in first place

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2
Q

Antibody

A

GlycoPROTEIN binds w/ antigen “lock & key”
Produced by B cells and plasma cells in response to a foreign substance exposure
Aka immunoglobulins

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3
Q

Immunogen

A

Any substance that is capable of inducing a humoral or cellular IR and combine with it

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4
Q

Immunoglobulin structure

A

Y shaped - 2 heavy chains & 2 light chains (kappa, lambda)
2 Fab regions
1 Fc region
The larger the hinge region the greater the chances of degredation

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5
Q

Fab

A

Antibody binding region of monomer.

Contains 1 heavy and 1 light chain

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6
Q

Fc

A

Crystallizable region. Contains 2 heavy chains. Complement fixation occurs here

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7
Q

Immune system

A

Defense mechanism
Mammels - rid host of pathogens
Invertebrates - some immune response
Ability to distinguish self

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8
Q

Recognition phase

A

Self ➡️ normally no I.R.

Non-self ➡️ response phase

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9
Q

Innate (natural) immunity

A
Most primitive 
General recognition
Antigen independent
First line
Rapid
Non-specific (physical and chemical barriers)
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10
Q

Adaptive (acquired) immunity

A
  • specific recognition of small portion of organism or antigen (antigen dependent)
  • memory of initiator
  • eliminate self reacting cells
  • 2 types: humeral and cell mediated
  • lag time between exposure and Max response
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11
Q

Autoimmunity

A

When self-reacting cells persist and are not destroyed.
Abnormal I.R. to host’s cells or tissue.
Antibody or cell mediated

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12
Q

Innate immune defenses in body

A
Flushing of urinary tract, pH
GI Flora
Stomach acid pH
Antimicrobial in saliva, tears
Physical barriers: cillia, mucus
Skin - fatty acids, Flora
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13
Q

Leukocytes

A

Wbcs

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14
Q

Neutrophils (polymorphonuclear neutrophilic leukocyte) PMN

A

Removes infectious agent by phagocytosis

Most abundant in circulation 55-75% of wbcs

Granulocyte

Nucleus

- mature PMN - multi-lobed (segmented)
- immature PMN - non-segmented bands
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15
Q

Monocytes

A

2-9% of wbcs

Agranulocytes

Nucleus - convoluted and Lacy

Cytoplasma - large amount of grey/blue w/small purple granules

Quickly removed from bloodstream to tissues where they become macrophages and histiocytes.

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16
Q

Interleukins produced by T Helper 2’s

A

IL-4, IL-5, IL-6

All help activate B cells so they can become plasma cells and produce antibodies

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17
Q

Plasma cells

A

Differentiated B cell, no longer has membrane IgM or IgD

Each plasma cell secretes an antibody with a specific variable portion (matches with a specific epitope)

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18
Q

Memory B cell

A

Long-lived, circulate through blood to lymphoid tissues
Have high levels of complement receptors/adhesion molecules
Repeat activation of a Memory B cell much easier than Mature B cell

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19
Q

Epitope (antigenic determinant)

A

Structure on antigen that elicits antibody response

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20
Q

Isotype

A

Changes in constant region of heavy chains which results in different classes of immunoglobulins (IgG, IgM, IgD, etc)

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21
Q

Allotype

A

Minor changes in constant region of heavy chains that create subclasses (IgG1-4)

22
Q

Idiotype

A

Changes in hypervariable region (both heavy and light chains) which changes which epitope is recognized (could be different parts of same antigen)

23
Q

IgG

A

80% of all immunoglobulins

Monomer, long-term immunity, only Ig to cross placenta, activates classical pathway, has 4 subclasses

24
Q

IgA

A
10-15% total Ig
2 subclasses (serum IgA usually a monomer, secretory IgA usually dimer or tetramer with secretory piece)
25
Q

IgM

A

5-10% of all Ig
Pentamer joined by J chain, first Ig produced in immune response, sometimes found in secretions, large size makes it good activator or complement
Effective in microbial killing

26
Q

IgD

A

0.2% of all Ig
Monomer, membrane-bound to mature B cells, long hinge region makes it prone to proteolysis
Regulates activation of B cells

27
Q

IgE

A

Less than 0.002% of all Ig
Binds mast cells/eosinophils at Fc region, binds allergen and caused degranulation (histamine released to cause allergic response), immune response to parasites

28
Q

Classical complement pathway

A

Antibody-dependent, components numbered C1-9
Recognition: C1q, C1r, C1s
Activation: C4, C2, C3
Membrane attack complex: C5-C9

29
Q

Membrane attack complex (MAC)

A

C5 cleaved to C5a (potent anaphylatoxin) and C5b (binding molecule for C6-9)
C6-7 deposit on cell membrane, lysis begins when C8 is added and forms channel, C9 completes channel (lysis due to uncontrolled loss of nutrients and influx of water)

30
Q

Alternate complement pathway

A
Antibody-independent
Factor D = similar to C1qrs
Factor B = similar to C2
Properdin = stabilizing molecule
Once C3 is cleaved, follows same path and classical
31
Q

Mannose-Binding Lectin (MBL) pathway

A

Innate immune system, important in infants who don’t have mom’s antibodies any more but don’t have own immune system, binds to carbohydrates

32
Q

Total Hemolytic Complement (CH50) assay

A

Checking patient ability to myself standard amount of antibody coated sheep RBC’s
If low, a factor is deficient
If 0, no complement at all

33
Q

AH50 Assay

A

Alternate pathway function, use rabbit blood
If both CH50 and AH50 abnormal, defect is in C3, or C5-9
If only CH50 abnormal, defect in C1, C2, or C4

34
Q

Macrophages

A

Large, round nucleus w/ 1-2 nucleoli

Cytoplasm - vacuolated w granules

Specialized in tissue

35
Q

Specialized macrophages

A
Dust cell - lung
Kupffer cell - liver
Mesangial phagocyte - kidney
Microglial cell - brain
Osteoclast - bone
36
Q

Natural killer cells

A

10-15% of lymphocytes
Destroy virus- infected and tumor cells
Lack antigen specificity

37
Q

Basophils

A

Inflammatory cells circulating

38
Q

Mast cells

A

Inflammatory cells in tissue

39
Q

Eosinophils

A

Allergy, parasitic infections

40
Q

Antigen presenting cells (apc)

A

Dendritic cells (innate)
Macrophages (innate)
B-cells (adaptive)

41
Q

Major histocompatibility complex (MHC)

A

Aka human leukocyte antigen (HLA)
Must be on surface of APC for t-cell activation
Associated with organ and tissue rejection
Class 1 MHC - on most cells
Class 2 MHC - on APC

42
Q

Epitope

A

Specific site on the antigen to which antibody or T cell receptors bind. An antigen can have many

43
Q

Proteolytic enzymes

A

Pepsin - 2 fragments: 1 Fc & 1 F(ab)2

Papain - 3 fragments: 2 Fab & 1 Fc

44
Q

Primary lymphoid organs

A

Bone marrow - produces B cells over lifetime of host

Thymus - produces T lymphocytes until host reaches puberty (CD4:CD8 ratio is 2:1)

45
Q

Secondary lymphoid organs

A

Lymph nodes, SPLEEN, Peter’s patches

46
Q

Lymphocytes - wbcs

A

Significant role in IR
Small, round, 10-12um diameter
Round nucleus w/ dense nuclear chromatin
Scant, blue cytoplasma

47
Q

Primary IR

A

IgM 1st, IgG next after first exposure to antigen

IgM large and captures lots of antigen, but declines faster

48
Q

Secondary IR

A

Follows re-exposure to same antigen
Shorter response time
Larger quantities of IgG produced
- persists longer due to memory cells

49
Q

Active/acquired immunity

A

Infection/exposure to antigen (natural)

Vaccination (artificial)

50
Q

Passive immunity

A

Your own immune system not producing
IgG cross placenta
Abs secreted in breast milk
Injections of gammaglobulins and Abs

51
Q

Adoptive immunity

A

Depending on what patient “needs”
Anti-cancer treatment
Introduction of natural killer cells