LYMPHOID SYSTEM Flashcards
structured to recognize,
respond to, and destroy a wide variety of invading organism that would otherwise be capable of promoting infections, harmful to the body
IMMUNE SYSTEM
ability of an individual to
resist infections by means of normally present body functions.
natural immunity
type of resistance that is
characterized by specificity for each individual pathogen, or microbial agent.
acquired immunity
represents 20-40% of the circulating
WBCs. Considered as the 2nd dominant circulating WBC in the bloodstream next to neutrophil.
lymphocytes
is sparse, containing few organelles and
no specific granules, and consists of a narrow ring surrounding the nucleus
Cytoplasm
Lymphocyte circulation is complex and is regulated by different cell surface adhesion molecules and by chemical messengers called
cytokines
it’s function is for maturation of the B cell and T cell
Primary Lymphoid organs
If the lymphocyte matured in the thymus the cell is known as
T-cell
Example of primary Lymphoid organs
Bone marrow, thymus
Example of secondary Lymphoid Organs
Spleen, lymph nodes, appendix, tonsils, peyer’s patches
further maturation, differentiation,
proliferation of T cells and B cells.
secondary lymphoid organ
fills the core of all long bones and is the
main source of hematopoietic stem cells, which develop into different cell types
bone marrow
what are the 3 major population of lymphocytes?
T cell, B cell, Natural Killer Cells
portal of entry for macrophages
mucosal-associated lymphoid tissue
an organ which is small, flat, bilobed organ found in the thorax, or chest cavity, right below the thyroid gland and overlying the heart.
thymus
Largest secondary lymphoid organ.
spleen
makes up more than one-half of the total volume, and its function is to destroy old red blood cells
red pulp
comprises approximately 20 percent of the total weight of the spleen and contains the lymphoid tissue, which is arranged around arterioles in a
periarteriolar lymphoid sheath (PALS)
white pulp
occurs in the secondary tissue, but this is strictly
dependent on antigenic stimulation, while
formation of lymphocytes in the bone marrow is
antigen-independent
lymphopoiesis
When antigen entered the spleen, it will activate B cells and form a structure known as the
germinal center
Germinal center is also known as
Secondary follicle
The lymph fluid flows slowly through spaces called
sinuses
main function of lymph nodes
filtration
Contains macrophages and aggregations of B cells in primary follicles, follicular dendritic cells, secondary follicles (germinal center), plasma cells, and memory cells
cortex
T lymphocytes are in close proximity to antigen presenting cells called
interdigitating cells.
physiological mechanisms that endow the
animal with the capacity to recognize materials as foreign to itself and to neutralize, eliminate or metabolize them with or without injury to its own tissues.
immunity
Serves as an antigen trapping site. Increase the probability of an immune response
Secondary Lymphoid Organs
main source of hematopoietic stem cells, which develop into different cell types.
bone marrow
released from the marrow
and travel to additional primary lymphoid organs
where further maturation takes place.
Lymphocyte stem cells
T cells percentage
61-80%
B cells percentage
20%
Natural Killer Cells percentage
10-15%
predominant in the bone marrow compared
to other cells.
WBC
In thymus, what cell play a central role in this differentiation process.
epithelial cells
acquired as the lymphocytes travel from the cortex to the medulla
Surface antigens
2 major parts of thymus
- cortex
- medulla
What lymphocytes are released from the medulla
Mature T lymphocytes
Each of these lines has specific precursors that
originate from
Bone Marrow
characterized as a large discriminating filter,
as it removes old and damaged cells and foreign
antigens from the blood
Spleen
Splenic tissue can be divided into two main
types
- red pulp
- white pulp
It contains B cells that are not yet stimulated
by antigens.
primary follicles
What surrounds the periarteriolar lymphoid sheath or PALS
marginal zone
marginal zone contains _____ that trap antigen
dendritic cell
increases its diameter accumulate
more lymph fluid that contains antigen
Afferent lymphatic
decrease its diameter for better trapping of antigens
efferent
lymphatic
Accumulation of lymphocytes
and other cells causes the lymph nodes to become
enlarged, a condition known as
lymphadenopathy
Located along lymphatic ducts and serve as central
collecting points for lymph fluid from adjacent tissues.
Lymph Nodes
Outermost region
Cortex
Located between the cortex and medulla region
Paracortex
contains inactivated B cells
Primary follicle
contains activated B cells
Secondary follicle
Less densely populated
Medulla
located at the junction of the small and
large intestines
appendix
Some T cells, B cells and numerous plasma cells are
found in this region.
medulla
located at the lower ileum of
the intestinal tract
Peyer’s patches
lymphoid tissue found in the mucous membrane lining of the oral and pharyngeal cavities.
tonsils
Organs associated with MALT
- appendix
- tonsils
- payer’s patches
contains a number of intraepidermal
lymphocytes.
Epidermis
differentiate into memory cells and plasma cells and are responsible for
Humoral immunity or antibody production
B cells
play a role in Cell-mediated
immunity, and as such, they produce sensitized lymphocytes that secrete cytokines
Cell-mediated Immunity
small polypeptides that
regulate the functions of lymphocytes and
other cells involved in the immune response
cytokines
Proteins that appear on cell surfaces can be used as
markers to differentiate T cells and B cells
surface markers or surface markers on lymphocytes
CD markers for Mature T cells
CD2, CD3, CD4 or 8
CD markers for Mature B cells
CD19, CD21, CD23
CD marker that was first discovered in Acute
Lymphoblastic Leukemia.
CD10
First step is the rearrangement of genes that code for
the heavy and light chains of an antibody molecule.
Pro B cell
The end result is a B lymphocyte programmed to
produce
antibody
heavy chains are coded on
chromosome 14
coded on chromosome 2
KAPPA light chain
coded on chromosome 22
LAMBDA light chain
The pro-B cell has distinctive markers that include
surface antigens
CD19, CD45R, CD43, CD24, and c-Kit.
found in Intracellular proteins
- terminal deoxyribonucleotide transferase
- recombination-activating genes RAG-1 and RAG2
immunoglobulin in pre b cell
IgM
The first heavy chains synthesized are the __
mu chain
What CD marker lose in pre b cell
CD43
Pre-B cells may also express μ chains on the cell
surface, accompanied by an unusual light chain
molecule called
surrogate light chain
surrogate light chain also known as
immature light chain
The combination of the two heavy chains with the
surrogate light chains plus two very short chains form
pre-B cell receptor
what cells can proceed to immature b cells?
pre-B cells expressing the mu
heavy chains
Rearrangement of genetic sequence coding for light
chains on either chromosome 2 or 22
immature b cell
μ chains are
no longer detectable in the cytoplasm
immature b cell
surface marker that appear on the immature B
cell
CD21, CD40
receptor to EBV
CD21
where did immature B cells develop into mature
cells
spleen
Other immature B cells become
follicular B cells
Immunoglobulin in mature B cell
IgD
B cell is stimulated by antigen, it undergoes
transformation to
blast stage
The process of Blast stage forms memory cells and antibody secreting plasma cells is known as
antigen dependent phase
CD marker that appears on both T cell and B cell
CD25
CD23 acts as a receptor to which interleukin
Interleukin 2
It is nondividing, and after several days
of antibody production, they die without further
proliferation.
Plasma cells
Plasma cell has fully differentiated lymphocyte and has the function of
antibody production
A significant selection process occurs as maturation
takes place
T lymphocyte
thymus have two main
zones
Outer cortex – immature T cells
Inner medulla – mature T cells
Interleukin associated with critical for growth
and differentiation.
Interleukin 7
What are the cell included in Thymic stromal cells
epithelial cells,
macrophages, fibroblasts, and dendritic cells
immature T cell
is both negative in CD4 and CD8 marker
double negative stage
Rearrangement of the genes that code for the
antigen receptor known as
T cell receptor complex
Signaling by the β chain also triggers the
thymocyte to become
CD4 and CD8 positive
the complex that serves as the main part of
the T-cell antigen receptor.
CD3
chains that are collectively known as CD3
epsilon, delta, gamma, zeta
CD8+ T cells interact with antigen and MHC class ____
MHC class I
responsible for presenting and
processing antigen to CD4+ T cells
MHC
class II protein.
Third major subclass CD4+ T-Cell population
T regulatory cells
CD marker for T regulatory cells
CD4 and CD25
Plays an important role in suppressing the immune
response to self-antigen
T regulatory cells
Third population lymphocytes
NATURAL KILLER CELLS
These lymphocytes are generally larger than T cells
and B cells at approximately 15 μm in diameter, and
they contain kidney-shaped nuclei with condensed
chromatin and prominent nucleoli.
NKC
A second method of destroying target cells is also
available to NK cells.
Antibody-Dependent Cellular Cytotoxicity
antibody responsible for
ADCC of NK cell.
IgG
Binding occurs through
CD16 and IgG
identify cell size
Forward light scatter
Lymphocytes are separated from whole blood
and then mixed with a suspension of sheep red
blood cells
rosette test
An automated system for identifying cells based on
the scattering of light as cells flow in single file through
a laser beam
cell flow cytometry
Fluorescent antibodies are used to screen of
subpopulation of T and B cells
cell flow cytometry
Use monoclonal antibodies. Unknown antibody which is fixed
Direct immunofluorescence
Use of unlabeled antibody. HAs a known antigen
Indirect immunofluorescense
