Immunodeficiency

Question 1

Name 3 mechanisms by which antibodies bind to antigens to enhance phagocytosis

Answer 1

Neutralisation
Agglutination
Precipitation

Question 2

Name the mechanism direceted by antibodies that enables cell lysis

Answer 2

Activation of complement system

Question 3

How to cytotoxic T cells act?

Answer 3

Bind to infected cells and perforin makes holes in infected cell’s membrane and enzyme enters. Infected cell is destroyed.

Question 4

What are the cytokines released by innate cells that direct the immune system to carry out more appropriate response

Answer 4

Pathogen associated molecular patterns (PAMP) e.g. directs T cells to develop into Th1, Th2 or Treg

Question 5

Primary immunodeficiencies

Answer 5

Genetic defect in component of immune system

Question 6

Secondary immunodeficiencies

Answer 6

Secondary to the effects of external factors

Question 7

IRAK4 deficiency -PRR activation defect

Answer 7

TLRs become activated and trigger a cascade of cytokine release- IRAK is essential in the production of an inflmmatory response- as adaptive immune system develops, other pathways offer protection-most severe in early life.

Question 8

Chronic granulomatous disease

Answer 8

Defect in phagocytosis affecting primarily males. AR. Neutrophils are unable activate proteolytic enzymes in phagosome. Defect in NADPH-oxidase complex-transports H+ across phagosome membrane.

Question 9

Diagnosis of chronic granulomatous disease

Answer 9

Nitroblue tetrazolium test- normally neutrophils release oxygen radicals which converts blue dye to black. Defect = no chance in colour

Question 10

Clinical presentation of CGD

Answer 10

Osteomyelitis, pneumonia, swollen lymph nodes, ginigivitis-gum disease, non malignant granuloma, inflammatory bowel disease

Question 11

Which complement pathways activate C5 to form pores in bacterial cell wall?

Answer 11

All 3

Question 12

Diagnosis of complement deficiency

Answer 12

Sheep RBCs incubated in patient’s serum-in competent terminal pathway- lysis of RBCs.

Question 13

Clinical presentation of complement deficiency

Answer 13

Meningococcal infections

Question 14

Treatment for people with complement deficiencies

Answer 14

Vaccines for meningococcal e.g. penicillin prophylaxis

Question 15

X linked agammaglobinaemia

Answer 15

Defect in B cells- antibody deficiency. Recurrent bacterial infections e.g. sino pulmonary infections. Usually diagnosed 1-2 yr, since maternal IgG protects.

Question 16

Treatment for X linked agammaglobinaemia

Answer 16

Treat with antibodies, then IgG for life

Question 17

Sever combined immunodeficiency (SCID)

Answer 17

Absent/reduced T cells and reduced B cells. Usually more severe than B cell defects, as B cells also need T cell help.

Question 18

Clinical presentation of SCID

Answer 18

Recurrent infections with opportunistic infections

Question 19

Treatment for SCID

Answer 19

Bone marrow transplant, gene therapy

Question 20

Infections caused in PRR activation defects

Answer 20

Pneumococcus, HSV

Question 21

Infections caused in phagocyte defects

Answer 21

CGD, staphylococcus aspergicillus

Question 22

Infections caused in complement defects

Answer 22

Meningococcus

Question 23

Infections caused in B cell defects

Answer 23

Recurrent sino-pulmonary infections

Question 24

Infections caused in T cell defects

Answer 24

SCID, opportunistic infections