Immune responses – humoral, cell-mediated, complement system - One Line Questions

1. What distinguishes adaptive immunity (humoral and cell-mediated) from innate immunity? — Adaptive immunity has memory and is highly specific.
2. Which pathway of complement activation is initiated by antigen-antibody complexes? — Classical pathway
3. The lectin pathway of complement activation is triggered by the binding of mannose-binding lectin (MBL) to microbial carbohydrates. What is MBL? —
4. Which cellular component is directly involved in the recognition of antigens by T lymphocytes? — T cell receptor (TCR)
5. The process of generating a large number of identical B cells or T cells that are specific for a particular antigen is called: — Clonal selection and expansion
6. Which immune cells are essential for recognizing and presenting antigens on MHC class I molecules to cytotoxic T cells? — Dendritic cells and all nucleated cells
7. Which immune cells are primarily responsible for recognizing and killing cells that are infected with viruses or are cancerous, especially those lacking MHC class I expression? — Natural Killer (NK) cells
8. Which complement protein acts as a potent anaphylatoxin, promoting inflammation and attracting immune cells? — C3a and C5a
9. Which component of the complement system is central to all three activation pathways and its cleavage generates fragments with critical functions? — C3
10. Which component of the complement system is responsible for forming the Membrane Attack Complex (MAC)? — C5b, C6, C7, C8, and C9
11. Which enzyme complex cleaves C5 to initiate the formation of the Membrane Attack Complex (MAC)? — C5 convertase
12. The formation of the C3 convertase enzyme is critical for amplifying the complement cascade. Which components form the C3 convertase in the classical and lectin pathways? — C4b2a
13. The alternative pathway's C3 convertase is formed by which components? — C3bBb
14. Which type of immune response primarily involves B lymphocytes and the production of antibodies? — Humoral immunity
15. Which complement pathway is considered part of the innate immune system and can be activated independently of antibodies? — Lectin pathway and Alternative pathway
16. Which pathway of complement activation involves the direct binding of complement proteins to the surface of a pathogen in the absence of antibodies or lectins? — Alternative pathway
17. Opsonization, a process that enhances phagocytosis, is a key function of which immune molecules? — Antibodies and complement proteins
18. Which specific type of T cell is responsible for downregulating immune responses to prevent excessive inflammation or autoimmunity? — Regulatory T cell (Treg)
19. Which type of T cell is responsible for recognizing and responding to antigens presented on MHC class II molecules? — T helper cell (CD4+)
20. What is the main function of T helper cells (CD4+ T cells) in cell-mediated immunity? — Activating other immune cells like B cells and cytotoxic T cells
21. What is the primary role of antibodies in humoral immunity? — Opsonize pathogens for phagocytosis, neutralize toxins, and activate complement
22. Cell-mediated immunity is particularly important for defense against: — Intracellular pathogens like viruses and some bacteria
23. Which immune response is primarily responsible for clearing intracellular pathogens like viruses and some intracellular bacteria? — Cell-mediated immunity
24. Cytotoxic T lymphocytes (CTLs or CD8+ T cells) are primarily involved in which type of immune response? — Cell-mediated immunity, by killing infected or cancerous cells
25. Which immunoglobulin (antibody) is the first to be produced during a primary immune response? — IgM
26. Which antibody isotype is predominantly found in mucosal secretions like saliva, tears, and breast milk? — IgA
27. Which immunoglobulin is involved in allergic reactions and defense against parasitic worms? — IgE
28. Which antibody isotype is most effective at activating the classical complement pathway? — IgM and IgG
29. Which of the following is a function of C3b, a cleavage product of C3? — Acting as an opsonin to promote phagocytosis
30. Which of the following is a characteristic feature of cell-mediated immunity? — Mediated by T lymphocytes
31. Which of the following describes the function of the complement system in lysis? — It forms the Membrane Attack Complex (MAC) that creates pores in pathogen membranes.
32. Which of the following is a key characteristic of humoral immunity? — It relies on antibodies produced by B lymphocytes.
33. In humoral immunity, what is the fate of a B cell that encounters its specific antigen and receives co-stimulatory signals from a T helper cell? — It differentiates into a plasma cell and/or a memory B cell.
34. The complement system's role in enhancing phagocytosis is known as: — Opsonization
35. The alternative pathway of complement activation is unique because it can be triggered without the involvement of antibodies. What initiates it? — Spontaneous C3 hydrolysis or direct interaction with pathogen surfaces
36. What is the term for the process where antibodies bind to antigens, preventing the pathogen from infecting host cells? — Neutralization
37. Memory cells are crucial for adaptive immunity. Which cell type is primarily responsible for long-term immunological memory in humoral immunity? — Memory B cells
38. What is the role of MHC class I molecules in cell-mediated immunity? — Present intracellular antigens (e.g., viral peptides) to cytotoxic T cells
39. What is the main function of MHC class II molecules in adaptive immunity? — Present extracellular antigens (e.g., bacterial peptides) to T helper cells
40. What is the key difference between primary and secondary immune responses? — Primary response is faster and stronger due to memory cells.
41. What is the primary outcome of complement activation via the classical, alternative, or lectin pathways? — Cleavage of C3 into C3a and C3b
42. What is the primary mechanism by which cytotoxic T lymphocytes (CTLs) induce apoptosis in target cells? — Releasing perforin and granzymes
43. What is the biological significance of antibodies binding to bacterial toxins? — They neutralize the toxins, preventing them from harming host cells.
44. What is the role of cytokines in immune responses? — To act as signaling molecules that regulate immune cell activity and communication
45. What is the role of antigen-presenting cells (APCs) like macrophages and dendritic cells in cell-mediated immunity? — To process and present antigens to T lymphocytes
46. What is the function of the anaphylatoxins (C3a, C5a) generated during complement activation? — To promote inflammation by increasing vascular permeability and attracting leukocytes
47. What is the function of regulatory T cells (Treg cells) in cell-mediated immunity? — To suppress the immune response and prevent autoimmunity
48. What is the primary function of antibodies in preventing viral infections? — To prevent viruses from binding to host cell receptors
49. What is the role of plasma cells in humoral immunity? — To produce and secrete large amounts of antibodies
50. What is the role of perforin, released by cytotoxic T lymphocytes? — To form pores in the target cell membrane, allowing granzymes to enter
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