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Questions and Answers
What primarily causes the death of CD4+ T cells during HIV replication?
What primarily causes the death of CD4+ T cells during HIV replication?
Which of the following infections is most commonly associated with AIDS?
Which of the following infections is most commonly associated with AIDS?
What is a defining characteristic for the diagnosis of AIDS?
What is a defining characteristic for the diagnosis of AIDS?
Which pathogen is typically isolated in AIDS patients experiencing diarrhea and weight loss?
Which pathogen is typically isolated in AIDS patients experiencing diarrhea and weight loss?
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Which neurological complications in AIDS can be attributed directly to HIV infection?
Which neurological complications in AIDS can be attributed directly to HIV infection?
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What is the CD4+ T cell count threshold that indicates the progression to AIDS?
What is the CD4+ T cell count threshold that indicates the progression to AIDS?
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Which condition is associated with severe wasting and diarrhea in AIDS patients?
Which condition is associated with severe wasting and diarrhea in AIDS patients?
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Which type of hypersensitivity reaction is impaired in AIDS patients?
Which type of hypersensitivity reaction is impaired in AIDS patients?
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Which malignancy is notably common in individuals with AIDS?
Which malignancy is notably common in individuals with AIDS?
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How do opportunistic infections contribute to morbidity in AIDS?
How do opportunistic infections contribute to morbidity in AIDS?
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Study Notes
Characteristics of Adaptive Immunity
- Adaptive immunity has four key immunologic attributes: antigenic specificity, diversity, immunologic memory, and self/non-self recognition.
Antigenic Specificity
- Vaccination illustrates antigenic specificity as it provides acquired immunity specific to pathogens, such as poliomyelitis virus, without cross-protection against unrelated viruses like influenza.
- Annual influenza vaccinations must target the specific strains due to antigenic variation.
Diversity
- The immune system can generate immense diversity in antigen-recognition molecules (B- and T-cell receptors), enabling recognition of billions of unique epitopes from foreign antigens.
Immunologic Memory
- After exposure to a specific antigen, the immune system retains a memory, leading to a more robust response upon subsequent encounters with the same antigen.
Self/Non-Self Recognition
- The immune system distinguishes self from non-self, responding only to foreign molecules. Misrecognition can lead to autoimmune diseases, some of which may be severe or fatal.
Transplantation Immunology
- Successful transplantation of solid tissues requires immunological compatibility between donor and recipient to minimize rejection.
- Immunosuppressive drugs can facilitate transplant acceptance but may increase infection risk and other health issues.
Types of Transplants
- Autografts: Tissue transplants from the patient to themselves.
- Isografts: Tissue transplants between genetically identical individuals (e.g., identical twins).
- Homografts (Allografts): Transplants between genetically non-identical individuals of the same species.
- Xenografts: Tissue transplants between different species (e.g., pig to human).
Transplant Rejection
- Rejection of homografts/allografts occurs due to antibody-mediated and delayed cellular immune response.
- Types of rejection:
- Hyperacute: Sudden, due to preformed antibodies against the donor's antigens, occurring during surgery.
- Acute: Typically occurs within weeks; can happen later if immunosuppressive therapy fails.
- Chronic: Develops slowly over months or years; involves both antibody- and cell-mediated responses.
Common Immunosuppressive Therapies
- Cyclosporine inhibits IL-2 production, affecting T-cell responses.
- Cyclophosphamide inhibits lymphocyte proliferation.
- Antibodies targeting T-cell antigens reduce T-cell numbers.
Disadvantages of Immunosuppressive Therapy
- Increased risk of infections.
- Side effects like nephrotoxicity from certain drugs (e.g., cyclosporine).
- Heightened cancer risk associated with immunosuppression.
Blood Transfusion Compatibility
- Blood transfusions depend on the compatibility of donor and recipient's RBC blood group antigens.
- Major blood group antigens include ABO system and Rh factor, with potential complications from minor blood group antigens.
ABO Blood Group System
- Four blood groups: A, B, AB, and O based on the presence of A and B oligosaccharides.
- Each group has corresponding natural antibodies; Group AB lacks natural antibodies against A/B antigens.
Severe Combined Immunodeficiency (SCID)
- Results from defects in lymphoid development affecting T/B cells, leading to severe immune dysfunction.
- Thymic aplasia is common, with very low circulating lymphocytes and diminished responsiveness to mitogens.
- High susceptibility to recurrent infections, often fatal in early childhood.
DiGeorge Syndrome (Congenital Thymic Aplasia)
- Characterized by absence of the thymus, resulting from a defect in embryonic development linked to chromosome 22 deletions.
- Innovative treatments using genetically modified lymphoid cells show promise in addressing this severe condition.
Secondary Immunodeficiency
- Nutritional deficiencies can compromise immunity by reducing cell-mediated immune function and CD4+ T helper cells.
- CD4+ T-cell destruction occurs in HIV infections, leading to a decrease in immune regulation.
AIDS Characteristics
- Opportunistic infections often seen, such as Pneumocystis carinii pneumonia and mycobacterial infections (e.g., tuberculosis).
- Neurological complications can arise from direct HIV effects or opportunistic pathogens.
Diagnosis of AIDS
- Confirmation of HIV-1 infection through antibody testing.
- CD4+ T cell counts below 200 cells/mm³ indicate severe immunosuppression.
- Presence of opportunistic infections and malignancies like Kaposi sarcoma.
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Description
This quiz explores the four main immunologic features of adaptive immunity: antigenic specificity, diversity, immunologic memory, and self/non-self-recognition. Understanding these concepts is crucial for comprehending how vaccinations and acquired immunity work. Test your knowledge on the fundamentals of adaptive immunity.
