HLA and PLT antigens Flashcards
WBC’s and platelets of allogenic origin can produce
immune response similar to seen when giving allogenic RBC’s
platelets and WBC’s both have ____ antigens but most has absorbed onto their surface from plasma, so much less than RBC’s
ABO
what is present on their surface as well
HLA (MHC) class 1
hla
human leukocyte antigens
MHC
major histocompatibility complex
1st importance for bone marrow transplants
HLA
2nd concern for bone marrow transplant
ABO
ABO still most important for other tissue grafts
class 1 genes are located on
most cells, but not RBC’s which is why we don’t consider them when transfusing rbc units
class 1 genes function as
self-recognition molecules for immune system, present antigen cytotoxic t-cells (CD 8)
class 2 genes are found on
cells in lymphocyte and monocyte lineages and and involved in antigen presentation to helper t-cells (CD4)
how is MHC class 1 encoded
HLA-A
HLA-B
HLA-C
found on short arm of chromosome 6
MHC 2 encoded by
HLA-DP
HLA-DQ
HLA-DR
what determines the specific peptide chains can be presented to T-cells
polymorphisms in alleles
individual can express up to
6 MHC 1 proteins
6 MHC 2 proteins
variation determines what antigens your immune system can present to t-cells
individual’s alleles act like
unique ID to immune cells
where are HLA important
transplantation
-matched as closely as possible to reduce GVHD
rbc’s have poor HLA expression so these antibodies don’t matter in RBC transfusion
how is HLA testing done
PCR
are HLA antibodies naturally occuring
no
typically formed in response to pregnancy
-antigen of paternal origin
what percent of patients develop an anti-HLA antibody following a pregnancy
20-35%
what percent of patients develop one when given a single-donor platelet unit
50%
-pretty antigenic
is cross reactivity common with HLA antibodies
yes
this is detected via ELISA
platelet specific antigens are found on
surface glycoproteins
-specific heterodimers are present on platelets
HPA- 1a and HPA - 1b are
antithetical
-most are located on GP111a or GP11b
-dozen known antigens most low incidence/high incidence pairs
platelet antibodies can cause both
refractoriness to platelets and post transfusion purpura
ex. Anti-HPA-1a typical culprit
