Module 4 Flashcards
(35 cards)
what are the adaptive immune systems
humoral and cellular with two classes of specialized cells
t lymph and b lymph (becomes plasma cell) that form from a stem cell
what do lymphocytes do
- recognize foreign antigens
-directly destroy some cells
-produce antibodies as plasma cells
what are the primary and secondary lymphoid tissues
primary: thymus , bone marrow -fetal liver
secondary - spleen, lymph nodes, peyers patches in the intestine
what is the function of the thymus
- t cell development
-in the lymphatic system
-as you age the thymus changes
reduction in thymus production of naive cells
-intrinsic defects in mature T cell function
-life span on naive T cells and memory T cells are altered-decline in T cell response in older people
-increased susceptibility to infections, autoimmune disease and neoplasms
-shrinks in size as you age
what is the role of the thymus in t lymph maturation
-lymphocytes travel from bone marrow to thymus to mature and become specialized
- the thymus is part of the endocrine system (production and release of hormones)
- regulates immune function secreting soluble hormones
- secretes thymosin- helps make specialized t cells (proliferation and differentiation)
-secretes thymocytes - immature t cells have acquired membrane antigens (from bone marrow and to the thymus to mature)
-the reticular structure of the thymus allows lymphocytes to pass through it and into the bloodstream -
-phagocytosis kill immature cells and any viable cells migrate to secondary tissues
what happens if there is an absence in thymus development
-causes t lymph deficiency
-presents as changes in immune system
if there is abnormal thymus development
there is a dysfunction of t and b lymph
-increases autoantibodies and monoclonal gammopathies
what is the function of the bone marrow
-contained in spongy bone
- source of progenitor cells
- can differentiate into lymph and other hematopoietic cells
what are the secondary lymphoid tissues
- lymph nodes
- have a lymphoid filter and replenish lymph fluid
spleen
-filters blood by removing cellular waste and old white blood cells
-gut associated lymphoid tissue (GALT)
- peyers patches (pre B lymph) in intestines and liver
-help with lymphocyte recirculation
-thoracic duct
- the thoracic duct lymph -rich source of mature T cell
secondary lymph tissue
bronchus associated lymphoid tissue - BALT
-secondary lymph tissue in lower respiratory tract -inhaled
antigen
-skin associated lymphoid tissue
- antigens introduced through the skin are presented by epidermal cells
- epidermal cells interact with lymphocytes in the skin and drain lymph nodes
blood
- mature lymph circulate there
where are t cells distributed
-perifollicular and paracortical regions of lymph nodes
-medullary cords of lymph nodes
-periarteriolar regions of the spleen
-thoracic duct of circulatory system
where are b cells distributed
b cells multiply and populate
follicular and medullary (germinal) centers of the lymph nodes
-primary follicles and red pulp of the spleen
-follicular regions of the GALT
-medullary cords of the lymph nodes
what is the function of the secondary lymphoid tissue
- allow migration and interaction between antigen presenting cells (APCs) T and B lymphocytes, follicular dendritic cells (FDCs) and other stromal cells
- generation of humoral immune responses- proliferation of B/T cells in 2ndary lymph tissues is dependent on antigenic stimulation
-tumor necrosis factor TNF and lymphotoxin
- both are cytokines produced by T and B lymph are essential to formation/maintenance of secondary organs
how do T cells mature
- bone marrow progenitor cells mature in the thymus
-differentiation of T lymph starts in the thymus as thymocyte (immature T cell) with early surface markers - CD44 and CD25 that commit them to a cell linage (these two are from t cells)
-as thymocytes develop genes for antigen receptors are rearranged
-
-maturation takes 3 weeks when cells filter through thymus cortex to medulla and then enter through blood circulation
what do you find in the blood circulation
- mature T lymphs which can survive for months or years but the average life of B lymp is a few days
-naive lymphs that have not met their antigen
-memory cells - older t cells or B cells that were stimulated by antigen
what are the types of T cells
naive t cells - not encountered their antigen
regulatory t cell - prevents autoimmune disease, modulates the immune system
memory t cell - heightened response after being REintroduced to a pathogen
T helper - with CD4 helps other lymphs to mature and activate
T killer - CD8 destroy virus infected cells and tumor cells
what are CD markers
Cluster of differentiation
-surface markers that identifies a cell line
CD4 - MHC CLASS 2 HELPER FUNCTION
CD8 - MHC CLASS 1 CYTOTOXIC FUNCTION - KILLER T CELLS
T CELL maturation cells
cd 44- increases activation of t cells
cd25 - t cell proliferation
early thymocytes dont have cd4 or cd8 and are called double negative thymocytes -outer cortex of thymus under interleukin 7 -growth and development
-rearrangement of gene for antigen receptor and beta chain create CD4 and CD8 thymocyte
what are double negative thymocytes
-dont have t cell receptors- CD4/CD8
-interleukin 7 needed for growth and differentiation
-can develop beta, gamma, and delta chains depending on their genetic makeup. The presence of the chains classify thymocytes are negative or positive and help regulate immunity
-people with increased CD4 and CD8 NEGATIVE (double negative lymphs) are those with autoimmune diseases, graft vs host disease (LOTS OF IMMATURATION)
what are double positive thymocytes
cells with both CD4 and CD8 POSITIVE
-increased double pos thymo indicative of inflammatory diseases , viral infections and cancer
what are helper T cells
Th1 - cell mediated effector mechanisms
Th2- regulation of antibody production
Treg (regulatory T cells) immunoregulatory type of Th cell
What are cytotoxic T lymph
capable of directly destroying virally infected target cells
-bind to infected cell antigen and use perforin or granzyme to make pores and cause cell death and apoptotic bodies
-suppressor T lymph - down regulate the action of other T and B cells
what NK cells
-lyse virus infected cells by antibody dependent cellular toxicity
-respond to CD markers
-granzymes -serine proteases released by granules in the cytotoxic t cells and NK cells
how are they different than cytotoxic t cells
- how they recognize their target - NK attack cells even if there is no surface marker but cytotoxic t cell need a surface marker to recognize their target and bind
what is the ration of help t to suppressor t
2:1
changes as you get older
-decrease in suppressor cells and increase in helper cells
-t cell subset type changes in the blood but the total number of t cells stays the same
issues with cell mediated immunity
impaired humoral response due to cytokine production impairment
igM decreases but igA IGG increases
