73 The Structure of Lymphocytes and Plasma Cells Flashcards
3 major blood lymphocyte functional subsets
T lymphocytes, B lymphocytes, and natural killer (NK) cells
Usual diameter of lymphoctes
6–15 μm
Small lymphocytes: 6–9 μm
Large lymphocytes: 9–15 μm
Mean absolute number of circulating small lymphocytes in normal adults
2.5 × 109/L
Children have higher lymphocyte counts that trend downward until they reach adult levels at about age_______years
8–10 years
What is the cell being described:
Slightly larger than most lymphocytes, with an increased area of light blue or clear cytoplasm; contains several coarse pink granules, usually 5–15 per cell, and occasional clear vacuoles
Large granular lymphocytes
In a normal adult, approximately 5% but up to 10% to 15% of blood lymphocytes are LGLs
The LGLs in blood are composed of NK cells and a subset of CD8+ T lymphocytes, indistinguishable by their morphology.
Infection with___________ causes an increase in blood lymphocytes with a particular activated morphology characterized by small size, scant cytoplasm, and cleaved nuclei with mature chromatin
B pertussis
TRUE OR FALSE
Cytoplasmic spreading does not occur in lymphocytes.
TRUE
Cytoplasmic spreading does not occur in lymphocytes.
Plasma cells derive from small _____ lymphocytes
B lymphocytes
The characteristic feature of plasma cells
Abundant cytoplasmic and secretory Ig
TRUE OR FALSE
A fully mature plasma cell has surface Ig expression.
FALSE
A fully mature plasma cell lacks surface Ig expression.
Large electron-dense inclusions of plasma cells
Russell bodies
What is the cell being described:
Cell with characteristic basophilic cytoplasm and an eccentric nucleus; large paranuclear zone
Plasma Cell
The large paranuclear zone of plasma cells corresponds to
Golgi apparatus
Antigens restricted to cells of the B lineage
CD20, CD22, and Pax 5
A transcription factor that is a “master regulator” of B-cell development
Pax 5
The target of rituximab, a monoclonal antibody commonly used for treatment of B-cell neoplasms
CD20
The best-defined pan–B-cell surface antigen
CD19
B cells have distinctive activation requirements and high levels of CD44 and interleukin-5 receptor α
B-1 B cell
In addition to the CD antigens and Igs, B cells express the three major histocompatibility complex (MHC) class II antigens: ________________
DR, DP, and DQ
TRUE OR FALSE
Many B-cell differentiation antigens are expressed by the mature plasma cell, including CD20, Pax-5, surface Ig, and human leukocyte antigen class II antigens
FALSE
Many B-cell differentiation antigens are NOT expressed by the mature plasma cell, including CD20, Pax-5, surface Ig, and human leukocyte antigen class II antigens
Distinctive cell surface antigens of plasma cells
CD138 and CD38
Clonal plasma cells usually aberrantly lack expression of _____________
CD19 and CD27
TRUE OR FALSE
All lymphocyte progenitors originate in the marrow, but T lymphocytes have their own special organ for maturation—the secondary lymphoid tissue —whereas NK cells appear to differentiate in thymus
FALSE
All lymphocyte progenitors originate in the marrow, but T lymphocytes have their own special organ for maturation—the thymus—whereas NK cells appear to differentiate in secondary lymphoid tissue
Both CD4 and CD8 contain:
CD2, CD3, CD4, CD5, CD7, and TCR α/β
Antigens specific to:
CD4:
CD8:
Antigens specific to:
CD4: CD10, CD25, CD57 and Foxp3100
CD8: CD16, CD56, CD57, cytolytic enzymes101
NK cells are negative for
CD3, TCR (α/β or γ/δ)
γ/δ T cells are negative for
CD4
Three general stages of thymocyte maturation based on the surface CD4 and CD8 expression:
- Double negative- least-mature ( subcapsular area)
- Double positive
- Single positive- most-mature (medulla)
Surface antigens present on T lymphocytes of all stages
CD2, CD5, and CD7
“double-negative” thymocytes also express
Aside from CD2, CD5 and CD7
CD1a, cytoplasmic CD3, and terminal deoxynucleotidyl transferase (TDT)
Most common lymphocytes in blood
Mature helper T-cells
TRUE OR FALSE
Mature T cells express either CD4 or CD8, but not both
TRUE
Mature T cells express either CD4 or CD8, but not both
CD4 recognizes MHC ____
CD8 recognizes MHC ____
CD4 recognizes MHC class II
CD8 recognizes MHC class I
Coreceptors for HIV
CD4
CCR5 (CC chemokine receptor type 5)
CXCR4 (CXC chemokine receptor type 4)
Cells that induce immune tolerance, and follicular T-helper cells that promote B-cell maturation and differentiation in germinal centers
T-regulatory (Treg) cells
Treg and follicular T-helper cells (TFH cells) express: ___________
CD10 and CD57
Adult T-cell leukemia/ lymphoma expresses both _______and ______ and is associated with marked immunosuppression.
CD25 and Foxp3
Has characteristic clonal T cells that express CD10 and CD57 just like TFH cells, and this lymphoma is associated with polyclonal hypergammaglobulinemia and the expansion and proliferation of both B cells and CD21+ follicular dendritic cells.
Angioimmunoblastic T-cell lymphoma
Cells that exhibit critical roles in mucosal defense and in autoimmune disease pathogenesis.
T-helper-17 (TH17) cells
TRUE OR FALSE
The NK cell is defined as an effector cell that is MHC-restricted and has the capacity for spontaneous cytotoxicity toward various target cells
FALSE
The NK cell is defined as an effector cell that is not MHC-restricted and has the capacity for spontaneous cytotoxicity toward various target cells
TRUE OR FALSE
Most NK cells have LGL morphology . However, not all NK cells have LGL morphology, and not all LGL cells are NK cells. Many are cytolytic T lymphocytes
TRUE
Most NK cells have LGL morphology . However, not all NK cells have LGL morphology, and not all LGL cells are NK cells. Many are cytolytic T lymphocytes
Human NK cells characteristically express _____ and ______but not TCRα/β or TCRγ/δ, CD3, or CD4.
CD16 (FcγRIII) and CD56
Surface antigens of Treg cells
CD3, CD4, CD25, and cytoplasmic FoxP3
Predominant phospholipid in the lymphocyte plasma membrane
Phosphatidylcholine
A tyrosine kinase in B cells that plays a critical role in signal transduction via surface Ig receptors
Bruton tyrosine kinase
Serve as scaffolding for the assembly of kinases and other signaling molecules after antigen-receptor ligation
Have no intrinsic enzymatic activity
Adapter proteins
EX: B-cell linker protein (BLNK), Linker for activation of T-cells
TRUE OR FALSE
Plasma cells have a high DNA-to-RNA ratio
FALSE
Plasma cells have a high RNA-to-DNA ratio
Reflecting the plasma cell’s high-level synthesis of Ig
Pore-forming proteolytic enzyme
Perforin
Serine proteinases with specific pro-apoptotic activity
Granzymes
Cytotoxic lymphocytes possess serine-proteinase inhibitors, termed
Serpins
