3.1 Basic Principles of Immunology Flashcards
From the following, identify a specific component of the adaptive immune system that is formed in response to antigenic stimulation:
A. Lysozyme
B. Complement
C. Commensal organisms
D. Immunoglobulin (Ig)
D. Immunoglobulin (Ig)
Ig is a specific part of the adaptive immune system and is formed only in response to a specific antigenic stimulation. Complement, lysozyme, and commensal organisms all act nonspecifically as a part of the adaptive immune system. These three components do not require any type of specific antigenic stimulation.
Which two organs are considered the primary lymphoid organs in which immunocompetent cells originate and mature?
A. Thyroid and Peyer patches
B. Thymus and bone marrow
C. Spleen and mucosal-associated lymphoid tissue (MALT)
D. Lymph nodes and thoracic duct
B. Thymus and bone marrow
##Footnote
Bone marrow and the thymus are considered primary lymphoid organs because immunocompetent cells either originate from them or mature in them. Some immunocompetent cells mature or reside in bone marrow (the source of all hematopoietic cells) until transported to the thymus, spleen, or Peyer patches, where they process antigen or manufacture antibody. T lymphocytes, after originating in bone marrow, travel to the thymus to mature and differentiate.
What type of B cells is formed after antigen stimulation?
A. Plasma cells and memory B cells
B. Mature B cells
C. Antigen-dependent B cells
D. Receptor-activated B cells
A. Plasma cells and memory B cells
##Footnote
Mature B cells exhibit surface Ig that may cross-link a foreign antigen, thus forming the activating B cell and leading to capping and internalization of antigen. The activated B cell gives rise to plasma cells that produce and secrete Igs and memory cells that reside in lymphoid organs.
T cells travel from bone marrow to the thymus for maturation. What is the correct order of the maturation sequence for T cells in the thymus?
A. Bone marrow to the cortex; after thymic education, release back to peripheral circulation
B. Maturation and selection occur in the cortex; migration to the medulla; release of mature T cells to secondary lymphoid organs
C. Storage in either the cortex or medulla; release of T cells into the peripheral circulation
D. Activation and selection occur in the medulla; mature T cells are stored in the cortex until activated by antigen
B. Maturation and selection occur in the cortex; migration to the medulla; release of mature T cells to secondary lymphoid organs
Immature T cells travel from bone marrow to the thymus to mature into functional T cells. Once in the thymus, T cells undergo a selection and maturation sequence that begins in the cortex and moves to the medulla of the thymus. Thymus factors, such as thymosin and thymopoietin, and cells within the thymus, such as macrophage and dendritic cells, assist in this sequence. After completion of the maturation cycle, T cells are released to secondary lumphoid organs to await antigen recognition and activation.
Which cluster of differentiation (CD) marker is the most specific identifying marker for mature T cell?
A. CD1
B. CD2
C. CD3
D. CD4 or CD8
C. CD3
The CD3 marker appears during the early stages of T-cell development and can be used to differentiate T cells from other lymphocytes.
Which markers are found on mature, peripheral helper T cells?
A. CD1, CD2, CD4
B. CD2, CD3, CD8
C. CD1, CD3, CD4
D. CD2, CD3, CD4
D. CD2, CD3, CD4
Mature, peripheral helper T cells have the CD2, CD3 (mature T cell), and CD4 (helper) markers.
Which T cells express the CD8 marker and act specifically to kill tumors or virally infected cells?
A. Helper T cells
B. Suppressor T cells
C. Cytotoxic T cells (Tc cells)
D. Regulator T cells
C. Cytotoxic T cells (Tc cells)
Tc cells recognize antigen in association with major histocompatibility complex (MHC) class I complexes and act against target cells that express foreign antigens. These include viral antigens and the HLAs that are the target of graft rejection.
How are Tc cells and natural killer (NK) cells similar?
A. Require antibody to be present
B. Effective against virally infected cells
C. Recognize antigen in association with human leukocyte antigen (HLA) class II markers
D. Do not bind to infected cells
B. Effective against virally infected cells
What is the name of the process by which phagocytic cells are attracted to a substance such as a bacterial peptide?
A. Diapedesis
B. Degranulation
C. Chemotaxis
D. Phagotaxis
C. Chemotaxis
All of the following are immunologic functions of complement except:
A. Induction of an antiviral state
B. Opsonization
C. Chemotaxis
D. Anaphylatoxin formation
A. Induction of an antiviral state
Which complement component is found in both the classic and alternative pathways?
A. C1
B. C4
C. Factor D
D. C3
D. C3
Which Ig(s) help(s) initiate the classic complement pathway?
A. IgA and IgD
B. IgM only
C. IgG and IgM
D. IgG only
C. IgG and IgM
How is complement activity destroyed in vitro?
A. Heating serum at 56C for 30 minutes
B. Keeping serum at room temperature of 22C for 1 hour
C. Heating serum at 37C for 45 minutes
D. Freezing serum at 0C for 24 hours
A. Heating serum at 56C for 30 minutes
What is the purpose of C3a, C4a, and C5a, the split products of the complement cascade?
A. To bind with specific membrane receptors of lymphocytes and cause release of cytotoxic substances
B. To cause increased vascular permeability, contraction of smooth muscle, and release of histamine from basophils
C. To bind with membrane receptors of macrophages to facilitate phagocytosis and the removal of debris and foreign substances
D. To regulate and degrade membrane cofactor protein after activation by C3 convertase
B. To cause increased vascular permeability, contraction of smooth muscle, and release of histamine from basophils
C3a, C4a, and C5a are split products of the complement cascade that participate in various biological functions, such as vasodilation and smooth muscle contraction. These small peptides act as anaphylatoxins, for example, effector molecules that participate in the inflammatory response to assist in the destruction and clearance of foreign antigens.
Which region of the Ig molecule can bind antigen?
A. Fragment antigen binding (Fab)
B. Fragment crystallizable (Fc)
C. Constant light (CL)
D. Constant heavy (CH)
A. Fragment antigen binding (Fab)
Fab is the region of the Ig molecule that can bind antigen. Two Fab fragments are formed from hydrolysis of the Ig molecule by papain. Each consists of a light chain and the V(H) and C(H1) regions of the heavy chain. The variable regions of the light and heavy chains interact, forming a specific antigen-combining site.
