ADAPTIVE IMMUNITY (GPT EDITION) Flashcards
What are the two main types of adaptive immunity?
Humoral immunity and cell-mediated immunity.
Where do B cells mature?
In the bone marrow
What is the primary function of B cells?
To produce antibodies for humoral immunity.
Where do T cells mature?
In the thymus.
What are the two main types of T cells?
Helper T cells (CD4+) and Cytotoxic T cells (CD8+)
What is the role of cytotoxic T cells?
To kill virus-infected cells and tumor cells.
What molecule is required for T cell antigen recognition?
The T cell receptor (TCR).
Which MHC class presents antigens to CD8+ T cells?
MHC class I.
Which MHC class presents antigens to CD4+ T cells?
MHC class II.
What are antigen-presenting cells (APCs)?
Dendritic cells, macrophages, and B cells.
What is clonal selection?
The process where only lymphocytes that recognize an antigen proliferate and differentiate.
What are memory cells?
Long-lived immune cells that provide rapid response to previously encountered antigens.
Which antibody is the first produced in an infection?
IgM.
Which antibody is the most abundant in blood?
IgG.
Which antibody is found in secretions like saliva and tears?
IgA.
Which antibody is involved in allergic reactions?
IgE.
What is opsonization?
The process where antibodies coat a pathogen to enhance phagocytosis.
What is the main function of regulatory T cells (Tregs)?
To suppress immune responses and prevent autoimmunity.
What is the function of perforin in cytotoxic T cells?
To create pores in infected cells, leading to apoptosis.
What cytokine stimulates T cell proliferation?
IL-2.
What is the difference between primary and secondary immune response?
Primary response is slow with mainly IgM production; secondary response is faster with IgG dominance.
What is affinity maturation?
The process by which B cells produce antibodies with increased antigen-binding strength.
What is the role of CD40 ligand (CD40L) in B cell activation?
It binds CD40 on B cells, helping their activation and antibody production.
What is somatic hypermutation?
A process in B cells that introduces mutations to improve antibody affinity
Which immunodeficiency is characterized by the absence of both B and T cells?
Severe Combined Immunodeficiency (SCID).
Which cells are primarily affected in HIV infection?
CD4+ T cells.
What is the Fas/FasL pathway?
A mechanism for apoptosis in immune regulation and cytotoxic T cell function.
What are superantigens?
Toxins that cause excessive activation of T cells, leading to cytokine storm.
What is the purpose of adjuvants in vaccines?
To enhance the immune response.
How do tumor cells evade immune detection?
By downregulating MHC molecules or producing immunosuppressive cytokines.
What is the difference between central and peripheral tolerance?
Central tolerance occurs in the thymus/bone marrow; peripheral tolerance occurs in mature lymphoid tissues.
What are the main cytokines secreted by Th1 and Th2 cells?
Th1: IFN-γ (activates macrophages), Th2: IL-4, IL-5, IL-13 (stimulate B cells and eosinophils).
What is cross-presentation in antigen processing?
The ability of dendritic cells to present extracellular antigens via MHC I to CD8+ T cells.
Which complement protein initiates the classical pathway?
C1q.
What is the difference between active and passive immunity?
Active immunity results from exposure to an antigen (infection/vaccine); passive immunity comes from antibody transfer (maternal antibodies, immunoglobulin therapy).
Which hypersensitivity type involves immune complexes?
Type III hypersensitivity.
What is molecular mimicry in autoimmunity?
When microbial antigens resemble self-antigens, leading to autoimmunity.
What is the role of dendritic cells in T cell activation?
They capture and present antigens to naïve T cells.
What is the key difference between a live-attenuated and inactivated vaccine?
Live-attenuated vaccines use weakened pathogens; inactivated vaccines use killed pathogens.
What is the role of Toll-like receptors (TLRs) in immunity?
They recognize pathogen-associated molecular patterns (PAMPs) and activate immune responses.
Why do infants rely on passive immunity early in life?
Their adaptive immune system is underdeveloped, so they receive maternal IgG and IgA.
What is immune exhaustion?
A state where chronic infections cause T cells to lose function.
Why do secondary immune responses generate more IgG than IgM?
Due to memory B cell activation and class switching.
What is the significance of the germinal center in lymph nodes?
It is where B cells undergo somatic hypermutation and class switching.
Why does immune tolerance break down in autoimmunity?
Due to genetic mutations, infections, or environmental triggers.
How do MHC molecules contribute to transplant rejection?
Mismatched MHC molecules trigger immune responses against transplanted tissue.
What is immune privilege?
Certain tissues (brain, eye, testis) avoid immune attacks to prevent damage.
What are regulatory B cells (Bregs)?
They suppress excessive immune responses and maintain tolerance.
How does cancer immunotherapy work?
It enhances the immune system’s ability to target and destroy tumors.
Why do elderly individuals have weaker immune responses?
Due to thymic involution, reduced T cell diversity, and weakened memory responses.
