Unit 3 Flashcards
Describe Pathological Immune Response
- Immune response is designed to protect individuals from invasion by foreign invasion: restore homeostasis
- Disease can rest if homeostasis is not maintained, therefore immune response may: overreact or react inappropriately to foreign invades (hypersensitivity), being to recognize self (autoimmunity) and be inhibited from operating (immune deficiency)
Hypersensitivity Reactions
Type 1 (allergy): antibody mediated Type 2 (cytotoxic hypersensitivity): antibody mediated Type 3 (Immune complex hypersensitivity): antibody mediated Type 4 (delayer hypersensitivity; DH): cell mediated
describe the types of tissue/organ transplants
- Allograft (most common): human to human (non identical twins, no rejection)
- Isograft (best case scenario): human to human (identical twins)
- Autograft (used in treatment of burns): region 1 to region 2
- Xenograft (used occasionally): human to animal
Describe self vs non-self transplants
- Cells of tissue express surface molecules (antigens) that identity cells as self: known as human leukocyte antigens (HLA)
- Immune systems strives to reject non-self: cells bearing different HLA antigens
- Rejection occurs when donor cells and recipient cells are mismatches (HLA mismatch)
- Rejection unlikely between matching HLA because it recognizes as self
Describe types of allografts
- Host vs graft (HVG): host immune system rejects the transplanted tissue (ex: kidney transplant)
- Graft vs host (GVH): graft tissues contain cells (lymphocytes) capable of mounting immune responses, immune cells present in graft recognize host tissue as foreign, host tissue are damaged therefore another graft can not be replaced and this causes a more damaged result
Describe transplant rejection mechanisms
- Transplant rejections is mediated mainly by Type 4 hypersensitivity: T cells are principles offenders that cause the graft rejections
- Humoral response participating
- Immune assault results in necrotic tissue damage within the graft
- Graft survival depends on: age or recipient, type of tissue used in graft, degree of HLA match between donor and recipient and administration of immunosuppressive drugs
Describe the classes of transplant rejections
- Hyperacute: occurs immediately (usually pre-existing antibodies) and damage occurs toolbox vessels resulting in ischemic damage
- Acute: occurs after several weeks, time required for host immune system to recognize tissue as non-self
- Chronic (late rejection): occurs after months or years (eventually happens about 10-15 years) , damage occurs to blood vessels resulting ins ischemic damage
Describe Therapeutic intervention in transplnatation
- Induction therapy: administered for first 2 weeks in post-op, combination rx: antibodies directed against T-cells, goal to prevent accelerated or acute rejection
- Initial therapy: administered 12 week in post op, combination rx: cyclosporine *can cause gingival hyperplasia
- Maintenance therapy: administered through lifetime, rx same as initial therapy but with reduced dosages
- Acute rejection: steroids administered as needed
Descrive Autoimmune Disorders
Recall *Immune system is supposed to ignore self: known as self tolerance
- Autoimmune disorders occur when: self tolerance mechanisms fail and immune response generated against self tissues
- May be mediated by antibodies ex: graves disease
- May be mediated by cells ex: Type I diabetes mellitus
Describe the aetiology of autoimmunity (4 things)
- Release of large amounts of tissue antigens after tissue damage
- Aging may result in breakdown tolerance
- Hereditary factors
- Infection and antigen mimicry
Transplant specific drugs
- prednisone and azathioprine: suppress the immune system to help prevent rejection to occurs
- side effects may be infection or cancer (our killer T cells can no longer monitor and destroy the bad cells
Describe immunodenficency disease
Results when one or more immune system functions is absent, damage or otherwise impaired. May be acute (short lasting) or chronic (long lasting)
Describe the effects of immunodeficiency disease
Increase susceptibility to infection
- Increase susceptibility to known pathogens
- Increase susceptibility to organisms not considered pathogens unless they have an opportunity (opportunistic infections)
- Increase likely hood of contracting certain cancers
- Due to loss of immunological surveillance function
Describe the 2 types of immunodeficiency disease
Primary (inborn):
-results from development malfunction: hereditary defect (mutation in DNA) and congenital defect (occurs in fetal development)
-prevents proper functioning os some aspects of host defences: innate and acquired (humeral or cell mediated)
-Severe combined immunodeficiency (SCID), chronic granulomatous disease (CGD) and DiGeorge syndrome
Secondary:
-occurs after exposure to agents that damage cells or tissues of immune system
-Agents may be chemical, physical, biological
-Damage may occur any time during lifetime
-Stress, surgery, malnutrition or liver disease, exposure to agents that prevent cell proliferation, cancer and infection (especially viral)
Describe Acquired Immunodeficiency syndrome
Recall * the centrality of TH cells to both B cell and T cell activation
-Infection with HIV causes loss of TH cells and the result is impairments to both humeral and cell mediated immune response
AIDs patients highly susceptible to:
- Opportunistic infections
- Certain cancers
