Lymphocytes Flashcards
CD marker found on all T cells and associated with T-cell antigen receptors
CD3
CD marker identifying T helper cells and also present on most T regulatory cells
CD4
CD marker identifying cytotoxic T cells and a subset of thymocytes
CD8
CD marker present on macrophages, NK cells, and neutrophils; mediates phagocytosis
CD16
CD marker on B cells and follicular dendritic cells; part of the B-cell coreceptor regulating activation
CD19
CD marker on B cells and follicular dendritic cells; receptor for complement component C3d
CD21
CD marker found on NK cells and subsets of T cells with unknown function
CD56
DNA polymerase active during immunoglobulin and T-cell receptor gene rearrangement
Terminal deoxynucleotidyl transferase (TdT)
Percentage of lymphocytes composed of T cells
60-79%
Primary immune function of T cells
Cell-mediated immunity
Products of T cells during immune response
Cytokines
Subtype of T cell responsible for activating the immune response and complement system
T helper cells (CD4+)
Subtype of T cell responsible for specific killing of infected cells
Cytotoxic T cells (CD8+)
Normal CD4:CD8 ratio in a healthy individual
‘2:1
CD4:CD8 ratio observed during HIV infection
‘1:2
Typical lifespan of T cells
4-10 years
Marker ratio used to identify T helper cells to cytotoxic T cells in normal conditions
CD4:CD8 ratio
Subpopulation of T cells that acts as the primary defense against autoimmune diseases
T regulatory cells
Type of T helper cell that produces IFN-gamma, TNF-beta, and IL-2 to protect against intracellular pathogens
T helper 1 (Th1)
Type of T helper cell that produces IL-4, IL-5, IL-6, IL-9, IL-10, and IL-13 to help B cells target extracellular pathogens
T helper 2 (Th2)
T helper cell type that produces IL-17 and IL-22 and is involved in pro-inflammatory responses
T helper 17 (Th17)
T regulatory cell markers
CD4 and CD25
Percentage of T regulatory cells in CD4 T-cell population
0.05
Primary role of T regulatory cells
Suppress immune response to self-antigens by secreting inhibitory cytokines
Stage of T-cell development characterized by cells lacking CD4 and CD8 but proliferating under the influence of IL-7
Double-negative thymocytes
Stage of T-cell development where both CD4 and CD8 markers are expressed and TCR genes are rearranged
Double-positive thymocytes
Process in double-positive thymocytes that removes cells reacting strongly to self-antigens
Clonal deletion
Marker present on mature T helper cells but absent on cytotoxic T cells
CD4
Stage of T-cell development characterized by expression of either CD4 or CD8 markers
Mature single-positive T cell
Receptor expressed by activated T cells under the influence of IL-2
CD25
Second largest population of lymphocytes (10-20%) responsible for humoral immunity
B cells
Markers associated with B cells
Surface Ig (IgM, IgD), CD19, CD20, CD21
Type of MHC molecule expressed on B cells but absent in T cells
Class II MHC
Cell type that is the precursor for antibody production in humoral immunity
Plasma cells
Subpopulation of B cells most commonly found in circulation
B2 cells
Life span of B cells compared to T cells
Days
Cell type in B cell development that requires direct contact with bone marrow stromal cells
Pro-B cell
Interaction required for Pro-B cell development involving stromal cells
C-Kit interacts with stem cell factor
First step in B cell development
Rearrangement of heavy-chain genes on chromosome 14
Chromosome associated with kappa light chain gene
Chromosome 2
Chromosome associated with lambda light chain gene
Chromosome 22
Cell type where synthesis of the heavy-chain part of the antibody molecule occurs
Pre-B cell
Unusual light chain molecule paired with the heavy chain in Pre-B cells
Surrogate light chain
Distinguishing marker of Immature B cells
Surface expression of IgM
Markers present on Immature B cells
CD21, CD40, and Class II MHC
Immunoglobulins present on Mature B cells
IgM and IgD
Receptor expressed on Activated B cells for IL-2
CD25
Main function of Plasma cells
Antibody production
Characteristic feature of Plasma cells
Eccentric nucleus with perinuclear halo
Key difference between B cells and Plasma cells regarding immunoglobulins
B cells: surface immunoglobulins; Plasma cells: cytoplasmic antibodies
Type of B cell involved in secondary immune response with antigen memory
Memory B cell
Locations where Follicular B cells are found
Secondary lymphoid organs, marginal zone of spleen, and circulation
Most fully differentiated form of B cells
Plasma cells
Marker that allows T cells to bind sheep red blood cells (SRBC)
CD2
Component of the T cell antigen-receptor complex
CD3
Receptor on T helper cells that binds MHC class II molecules
CD4
Receptor on cytotoxic T cells that binds MHC class I molecules
CD8
Gold standard for laboratory identification of lymphocytes
Flow cytometry
Microscopy method used to visualize fluorescence-labeled lymphocytes
Fluorescence microscopy
Test used to identify T cells by their ability to bind to sheep RBCs
Rosette assay
Centrifugation method used to separate lymphocytes from other blood components
Density gradient centrifugation (Ficoll-Hypaque)
Method used to separate T cells and B cells based on their properties
Nylon wool separation
Components in the layers of blood after Ficoll-Hypaque density gradient separation
Plasma, lymphocytes, Ficoll, red blood cells, granulocytes, platelets
Definition of mitogen in lymphocyte testing
A substance that stimulates mitotic division of lymphocytes, increasing their concentration
Mitogen used for T cell stimulation
Pokeweed antigen (PWA)
Mitogen used for T cell stimulation that induces mitosis and lymphocyte proliferation
Phytohemagglutinin (PHA)
Mitogen used for T cell stimulation that activates T lymphocytes
Concanavalin A (CON-A)
Mitogen used for B cell stimulation
Pokeweed antigen
Mitogen used for B cell stimulation that is a bacterial component
Lipopolysaccharide (LPS)
