Immunology Mendros

8/11/2019 Immunology Mendros

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Complement

System


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Characteristics of Complement

Plays a role in cytolytic action

Inactivated in the sera

IgG and IgM only react with complement

Bound to all antigen-antibody complexes

Found in all mammalian sera and lower

animals


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Complement is non-specific

portions of the system contribute to

chemotaxis, opsonization, immune

adherence, anaphylatoxin formation and

virus neutralization

Characteristics of Complement


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*chemotaxins - C5a, C5b, C6, C7

*for immune adherence - C3b

*kinin activator - C2b

*anaphylatoxins - C3a, C4a, C5a

*opsonins - C3b, C4b, C5b

*for virus neutralization - C4b, C1


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C1q C1r C1s

Antigen-IgG-complement

complex

Antigen-IgM-complement

complex

C1q C1r C1s


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b. C4- FIRST ACTIVATION UNIT

- cleaved into C4a and C4b

c. C2SECOND ACTIVATION UNIT

- cleaved into C2a and C2b

- C2a combines with C4 to form

C4b2a complex


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d. C3 - THIRD ACTIVATION

UNIT/AMPLIFICATION

PHASE UNIT- C3b combines with C4b2a to form C4b2a3b

e. C5, C6, C7, C8, C9 MEMBRANE ATTACK

PHASE UNITS


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ALTERNATIVE PATHWAY OFCOMPLEMENT ACTIVATION

a.Factor B activated into its active form Bb withthe participation of C3

-Bb will cleave C3 into C3a and C3b and will

combine with C3b to form C3bBb

b. Factor D- cleaves Factor B into Bb in the presenceof C3 and Mg++ ions

Therefore,

Factor B + Factor D + C3 + Mg++ C3bBb

c. Properdin (Factor P)- binds to C3bBb to prevent

spontaneous decay of the complex


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ACTIVATING FACTOR: MANNOSE GROUPS OF

CHO IN MICROBIAL CELL

EFFECTORS:

MBP/MBL- MANNAN-BINDING PROTEIN/LECTIN

MASP MBP-ASSOCIATED SERINE PROTEASE


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CLASSICAL ALTERNATIVE LECTIN

ACTIVATING

SUBS.

IMMUNE

COMPLEXES(IgG OR IgM)

LPS (bacterial

capsule)

IgA

Mannose

groups onmicrobial cell

RECOGNITIONUNIT

C1q, C1r, C1s C3, Factor B,Factor D

MBP, MASP-1,MASP-2

C3CONVERTASE

C4b2a C3bBb C4b2a

C5CONVERTASE

C4b2a3b C3bBb3b C4b2a3b

MAC C5b6789

END RESULT CELL LYSIS


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CLINICAL SIGNIFICANCE:

Elevatedcomplement components - have little clinical

importance

Decreasedcomplement componentsCauses : - complement has been consumed

(e.g. in disease states)

- complement may be decreased or absent due to

genetic defect

MEASUREMENT OF COMPLEMENT COMPONENTS


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DEFICIENT COMPONENT ASSOCIATED DISEASE

C1q Sex-linked agammaglobunemia

Hypocomplementemic urticarial

vasculitisSevere combined immune

deficiency

SLE-like syndrome

Increased susceptibility to

bacterial infection

C1r URT diseases

Chronic kidney disease

SLE-Like syndrome

C1s SLE-like syndrome


bacterial infection



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C1sINH Hereditary angioneurotic

edema

C4 SLE

Glomerulonephritis

Pyogenic Infections

C2 SLEDermatomyositis

Repeated Infectious

disease

Chronic renal diseaseAutoimmune disease


bacterial infection


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DEFICIENT

COMPONENT

ASSOCIATED

DISEASE

C3 Recurrent pyogenic

infections

SLE-like syndrome

Post-streptococcal

glomerulonephritisPyogenic infections

C3b inactivator Recurrent pyogenic

infections

Urticaria

C5 SLE

Neisseria infections



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C5 dysfunction Leinersdisease

Gram Negative skin and bowel

infections

C6 Neisseria infection

SLE

Raynaudsphenomenon

Sclerodermalike syndrome

Vasculitis

C7 Neisseria infectionSLE

Raynaudsphenomenon

Sclerodactyly

Telangiectasia


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DEFICIENT

COMPONENT

ASSOCIATED

DISEASE

C8 Neisseria infectionXeroderma pigmentosa

SLE-like syndromeC9 Neisseria infection

Properdin

Factor D

Pyogenic infections

Pyogenic infections


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CLINICAL SIGNIFICANCE:

ELEVATED LEVELS (ABOVE THE NORMAL 0.6 mg/dL) indicates:

- inflammation- tissue damage

AS SEEN IN

- bacterial and viral infections- rheumatic diseases such as RA- myocardial infarction- burn injuries

- tuberculosis- renal transplantation- malignancies


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Question 1

In the heterophil antibody test, when serum is

absorbed with beef cells

A. there is a decrease in the titer of IM antibodies

B. there is an increase in the titer of GPKCantibodies

C. Serum sickness are not absorbed

D. Forssman antibodies are absorbed

ANSWER : A


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QUESTION 3

Forssman antibodies are absorbed by :

A. boiled beef cells

B. Guinea pig kidney antigen

C. neither beef cells nor guinea pig kidney antigen

D. both beef cells and GPKC

ANSWER : B


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QUESTION 4

Which of the following represents the

reported titer in quantitative VDRL test ?

A. Lowest dilution giving a weakly reactive result

B. Lowest dilution giving a reactive result

C. Highest dilution giving a weakly reactive result

D. Highest dilution giving a reactive result

ANSWER : D


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QUESTION 7

How can cell-mediated immunity be

transferred to a normal individual ?

A. with lymphoid cells from a hypersensitive

individual B. with transfer of specific liver cells from an

infected individual

C. with transfer of monocytes from a normal

person D. with polymorphonuclear cells from a normal

person

ANSWER : A


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QUESTION 8

The random movement of antigen or antibody

to form antigen-antibody complexes in semi-solid medium occurs in :

A. agglutination

B. immunofluorescence

C. complement fixation

D. gel diffusion

ANSWER : D


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QUESTION 9

Interferon can be produced by which of the

following ?

A. macrophages

B. T-lymphocytes

C. virus-infected cells

D. All of the above

ANSWER : D


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QUESTION 11

When a precipitation reaction is converted to

agglutination by increasing the size of antigenparticles, the test is then referred to as :

A. direct agglutination

B. capillary precipitation

C. passive agglutination

D. hemagglutination inhibition

ANSWER : C


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QUESTION 14

The basic immunoglobulin structure consist

of:

A. 1 light and 2 heavy chain

B.2 light and 2 heavy chain

C. 2 light and 1 heavy chain

D. 1 light and 1 heavy chain

ANSWER : B


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QUESTION 15

After an antibody has been fragmented, which

term denotes the antigen binding fragment ?

A. Fc

B. disulfide bond

C. Fab

D. Carboxyl terminal

ANSWER : C


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QUESTION 16

A positive reaction in a complement fixation

test is expressed as ?

A. agglutination

B. hemolysis

C. inhibition of hemolysis

D. neutralization

ANSWER : C


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QUESTION 18

What does the ASO test measure in the

patient serum ?

A. Oxygen labile streptolysin

B. antibody to streptolysin O

C. Sheep red blood cells

D. Streptococcal antibodies

ANSWER : B


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QUESTION 20

The Widal and Weil-Felix reactions are

examples of techniques used to detect :

A. heterophil antibodies

B. reagin

C. febrile agglutinins

D. Forssman antigen

ANSWER : C


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QUESTION 21

What is the incubation temperature for the

cold agglutinin test ?

A. body temperature

B. room temperature

C. refrigerator temperature

D. freezer temperature

ANSWER : C


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QUESTION 22

The RPR test is rotated at what speed for what

length of time?

A. 200 rpm for 10 mins.

B. 100 rpm for 8 mins.

C. 180 rpm for 4 mins.

D. 125 rpm for 2 mins.

ANSWER : B


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QUESTION 23

What role does cardiolipin play in the VDRL test ?

A. it is the center for absorption of tissue lipids

B. it is related to the sensitivity of the test

C. it is related to the reactivity of the test

D. all of the above

ANSWER : C


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QUESTION 24

Which of the following cold reacting

antibodies is present infections ofMycoplasma pneumoniae ?

A. anti-I

B. antii

C. anti- Lewis

D. antiK

ANSWER : A


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QUESTION 26

A hapten is :

A. A carrier molecule for an antigen that is not

antigenic alone

B. A determinant capable of stimulating an IR onlywhen bound to a carrier

C. An immunoglobulin functional only in the

presence of complement D. Half of an immunoglobulin molecule

ANSWER : B


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QUESTION 27

Which of the ff. characteristics is not true for B

cells ?

A. become memory cells

B. Contain surface immunoglobulins

C. Differentiate into plasma cells

D. secrete the C5 components of complement

ANSWER : D


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QUESTION 28

THE HLA complex is located primarily on :

A. Chromosome 3

B. Chromosome 6

C. Chromosome 9

D. Chromosome 17

ANSWER : B


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QUESTION 29

What is the predominant type of antibody

found in the serum of neonates born afterfull-term gestation?

A. Infant IgA B. Infant IgD

C. Infant IgG

D. Maternal IgG

ANSWER : D


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QUESTION 30

Which class of immunoglobulin possesses 10

antigenic binding sites ?

A. IgA

B. IgD

C. IgG

D. IgM

ANSWER : D

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Immunology Mendros