Lymphoid Structures and Lymphoctes EC Flashcards
What occurs in the lymph node follicle? What is the difference between a primary and secondary follicle?
B-cell localization and proliferation
Primary follicles dense and dormant
Secondary follicles active with pale germinal centers
What occurs in the paracortex? When would this area be enlarged?
House T-Cells
Enlarged in extreme cellular immune response (ie virus)
would NOT be enlarged in DiGeorge (no thymus)
Lymph node drainage of the upper limb and lateral breast
Axillary nodes
Lymph node drainage of Stomach
Celiac nodes
Lymph node drainage of Duodenum and Jejunum
Superior mesenteric nodes
Lymph node drainage of Sigmoid colon
Colic then Inferior mesenteric nodes
Lymph node drainage of Rectum and Anal canal (above pectinate line)
Internal iliac nodes
Lymph node drainage of Anal canal below pectinate line
Superficial inguinal nodes
Lymph drainage of testes
Para-aortic nodes
Lymph drainage of scrotum
Superficial inguinal nodes
Lymph drainage of thigh
Superficial inguinal nodes
Lymph drainage of lateral dorsum of foot
Popiteal nodes
What does the Right lymphatic duct drain?
Right arm
Right chest
Right half of face
What does the thoracic duct train? Where does it drain?
All but R-arm, R-chest, and R-face
Drains at junction of Subclavian and Internal Jugular veins
Does lymphatic blockage result in pitting or non-pitting edema?
Non-pitting edema (filled with protein, fat, etc.)
Within the spleen, where are T-Cells found?
PALS (periarterial lymphatic sheath)
Within the spleen, where are B-Cells found?
In follicles
What is the function of macrophages within the spleen?
To remove encapsulated bacteria
“Even Some Killers Have Nice Shiny Bodies”
E. coli Strep. pneumoniae Klebsiella pneumoniae H. influenzae Neisseria meningitidis Salmonella B Strep
What findings are their post-splenectomy?
Howell-Jolly bodies (RBC nuclear remnants)
Target cells
Thrombocytosis (increased platelets)
Thymus appearance and selection that takes place in each region
Cortex is DENSE with IMMATURE T-Cells
~Positive Selection (MHC restriction)
Medulla is PALE with MATURE T-Cells
~Negative Selection (Nonreactive to self)
What are M cells?
Present in gut
Present antigens from gut to Lymphocytes
Innate Immune System
Nonspecific - No memory
PMNs, Macrophages, Dendritic Cells, NK cells, Complement
Adaptive Immune System
Receptors that recognize pathogen undergo V(D)J recombination during development
Response slow at first exposure, but fast and robust with memory
T-Cells, B-Cells and circulating antibody
MCH I
HLA-A, HLA-B, HLA-C
Binds TCR and CD8
Express on ALL NUCLEATED CELLS (ie not RBCs)
Antigen loaded into ER (intracellular peptides)
Viral immunity
MHC II
HLA-DR, HLA-DQ, HLA-DP
“Dr. went into DQ to get a Dr. Pepper”
Binds TCR and CD4
Expressed only on APCs (dendritic, macrophage, B-cell, M-cell)
Natural Killer Cells
Use Perforin and Granzymes to induce apoptosis in virally infected cells and tumor cells (similar to CD8 T cells)
Enhanced by IL-2, IL-12, IFN-beta, IFN-alpha
Kill with non-specific antigen or no MHC I expressed
B cell major functions
Make antibody Opsonize bacteria (IgG) Neutralize viruses (IgG) Activate complement (IgG, IgM) Sensitize mast cells (IgE)
Hyperacute and humoral organ rejection
T cell major functions
CD4 T cells:
Help B cells make antibody
Produce cytokines to activate other cells
CD8 T cells:
Kill virus infected cells and tumor cells
Acute and chronic cellular organ rejection
Naive T Cell activation
Foreign body phagocytosed by APC
Antigen presented on MHC and recognized by TCR
Costimulatory signal of B7-CD28
Helper T cell produces cytokines
Cytotoxic T cell activates, recognizes, and kills virus infected cell
B cell activation and class switching
B cell presents antigen on MHC II to TCR of CD4 cell
CD40 binds CD40L on T-cell
CD4 cell secretes cytokines that determine Ig class switching of B cell
Th1 CD4 Cells (Secrete, Activate what, Inhibited by)
Secrete IFN-gamma
Activate macrophages
Inhibited by IL-4 and IL-10 (from Th2 cell)
Th2 CD4 Cells (Secrete, Activate what, Inhibited by)
Secrete IL-4, IL-5, IL-10, IL-13
Recruits eosinophils for parasitic defenses
Promotes IgE production
Inhibited by IFN-gamma (from Th1 cell)
Cytotoxic T Cells
Release Perforin and Granzyme (killing virus infected cells and tumor cells)
Regulatory T Cells
Suppress CD4 and CD8 functions
Express CD3, CD4, CD25
Produce anti inflammatory cytokines IL-10, TGF-beta
Idiotype
Specific antibody that Ig binds
Isotype
Type of antibody
IgM vs IgG etc.
IgG
Delayed response to antigen (most abundant)
Fixes complement
Crosses placenta
Opsonizes bacteria
Neutralizes bacterial toxins and viruses
IgA
Prevent attachment to mucous membranes
Found in secretions
IgM
Early response to antigen
Fixes complement
Traps free antigens while humoral response evolves
IgE
Bind mast cell and basophil –> HISTAMINE release
Immunity to worms by activating eosinophils
Thymus-independent antigens
No protein content
Stimulate antibody release but NO MEMORY
Thymus-dependent antigens
Protein content
Stimulate class switching and MEMORY
