Lymphoid structures II Flashcards
What is the general structure of the spleen?
long vascular channels in red pulp with fenestrated basement membrane
macrophages found nearby to remove encapsulated organisms
Where are T and B cells found in the spleen? What about other APCs?
T cells in the periarterial lymphatic sheath in the white pulp
B cells are within the follicles in the white pulpb
other APCs are found in the marginal zone btween the white pulbe and the red pulp.
When might you see splenic dysfunction?
post-spenectomy, sickle cell disease
What is the problem with splenic dysfunction? What pathway leads to this problem?
problem: infections with encapsulated organisms
Decreased IgM causes decreased complement activation. There is decreased C3b opsonization and an increased susceptibility to encapsulated organisms
What organisms are most likely to cause trouble in a patient with splenic dysfunction? Be specific.
SHiNE SKiS
Strep pneumo, HiB, Neisseria meningitidis, E. coli, Salmonella, Klebsiella pneumo, Group B Strep
What might you see in the blood of a patient after a splenectomy?
Howell-Jolly bodies (RBCs with nuclear “spots”/”dots” in them), Target cells, thrombocytosis (high platelets)
What is the structure and embryonic origin of the thymus?
encapsulated lymphoid organ withOUT follicles
from the epithelium of the 3rd pharyngeal pouch
cortex has immature T cells and is dense. medulla has mature t cells and is pale.
Hassall corpuscles define the thymus.
MHCI vs. MHC II loci and structure (may try drawing this)
MHC class I molecules may be HLA-A, HLA-B, or HLA-C. The structure of the class 1 molecule looks like a clover. It passes through the membrane once, and has three alpha parts. the final section is filled by beta 2 microglobulin, which helps transport it to the cell membrane. MHC class II molecules may be HLA-DP, DQ, or DR The structure is one alpha chain and 1 beta chain (2 subunits each), with the peptide binding groove in the middle.
What diseases are associated with HLA-B27?
PAIR disease: psoriatic arthrits, ankylosing spondylitis, arthritis of inflammatory bowel disease, and reactive arthritis (Reiter syndrome: can’t pee, can’t see, can’t climb a tree)
What HLA subtypes are associated with celiac’s disease?
DQ2/DQ8
What HLA type is assochiated with hemochromatosis?
A3
What diseases are associated with DR2
MS, hay fever, SLE, goodpasture
What diseases are associated with DR3?
DM type 1, SLE, Graves
What diseases are associated with DR4?
rheumatoid arthritis, DM type 1
What diseases are associated with DR5?
pernicious anemia and Hashimoto thyroiditis
