Types Of Immune Responses 3 & 4

Question 1

Describe type 3

Answer 1

Ab: igG and igM
Ag: soluble exo or endo
3-8 hours after exposure to ag
May be localized or systemic

Question 2

How does type 3 occur

Answer 2

Ag binds to ab forming an immune complex
Ag-ab deposit in post capillary venules then complement fixation occurs
Leading to leukocyte recruitment with inflammatory reactions
Must have NECROTIZING VASCULITIS AND FIBRINOID NECROSIS AND TISSUE INJURY

Question 3

Describe systemic immune complex mediated disease

Answer 3

Type 3
Serum sickness
Acute self limited disease that occurs 6-8 days after injection of foreign serum for passive immunization
Fever arthralgia, vasculitis, acute glomerulonephritis

Question 4

Describe localized immune complex mediated diease

Answer 4

Type 3
Arthus reaction
Localized immune reaction
Induced vasculitis leading to an area of tissue necrosis
Elicited in skin after injection of an ag in sensitized individuals

Question 5

Describe type 4

Answer 5

Cell mediated hypersensitivity
T lymphocyte mediated destruction of cells along with dendritic cells,macrophages and cytokines
Delayed
Occurs 24 hrs after contact and starts at 2 or 3 days and often lasts for many days

Question 6

Describe cytokine mediated inflammation/delayed hypersensitivity reaction

Answer 6

Against persistent non degradable intracellular ag
Activated by CD4 T helper (1+17) and leads to release of IFN
Activate macrophages transformation to epithelioid cells and development of granuloma

Question 7

What is the tuberculin reaction

Answer 7

Also known as mantoux test
Purified mycobacertical ag administered in to skin of previously immunized individual and results in a detectable cutaneous reaction within 24 to 48 hours
Used as the basis of a diagnostic skin test for an immune response to TB

Question 8

What is the granuloma formation

Answer 8

Against intracellular non degradable ag
Mediated by CD4 th1 activation and production of cytokines as IFN-y and IL3 that stimulate macrophage production,activation and transformation to epitheloid cells

Question 9

Describe the reaction against fungal infection

Answer 9

Type 4
Mediated and activated by th17 that secrete il17 and il22
Recruit neutrophils and monocytes promoting inflammatory reaction

Question 10

Describe allergic contact dermatitis

Answer 10

Type 4
Reaction against poison ivy
Same mechanism responsible for most drug reactions

Question 11

Describe cell mediated cytotoxicity reaction and give examples

Answer 11

Mediated by CD8 t cells
Activated cytotoxic cells stimulate ig bearing cell apoptosis

Cytotoxic reaction against virus infected cells and malignant cells
Type 1 diabetes: killing of pancreatic islet cells by cytotoxic t cells resulting in insulin deficiency
Graft vs host disease and chronic transplant rejection

Question 12

What is organ transplantion

Answer 12

Process of moving cells tissues or organs from a donor to a recipient for the purpose of replacing repairing diseases or damaged tissue

Question 13

What is a rejection reaction

Answer 13

Occurs when the recipient’s immune system recognizes the donor’s HLA antigen system as foreign triggering immunological reaction against transplanted organ with destruction and failure of transplantation

Question 14

How are HLA antigens presented

Answer 14

By APC to t lymphocytes and b lymphocytes

Question 15

What is rejection mediated by

Answer 15

Type 4 cytotoxic t cell reaction
Delayed hypersensitivity reaction( CD4 mediated)
And b cell ab mediated injury depending on duration and presence of previous circulating abs

Question 16

How are patients matched

Answer 16

According to blood group
Tissue typing
And how recipient’s blood serum reacts to donor cells