Adverse Rxn & Molecular Testing Flashcards
HLA properties
- Present peptide to TCR (self-recognition & immunological defense)
- Polymorphic
- Co-dominant
- Mendelian rules
- Ethnical difference
- Patient create Abs against HLA protein
HLA Molecular Typing
- Genotyping
- RT- PCR
HLA Antibody Testing
- Luminex: Result (CPRA) sent to UNET - Higher number (percentage) means less compatible donor.
- Flow Cytometric Crossmatch
Application of HLA testing
- Organ transplantation
- PLT transfusion
- TRALI investigation
- Disease association/treament
Solid organ Tx vs HSC Tx
- Solid organ: avoid HLA Abs pre-formed from patient
- HSC: HLA matching to avoid GvHD
HLA & PLT Refractoriness
- When suspicious, pt is tested for HLA class I Abs
- Pt should receive HLA I -negative for that specific Abs
Strategies for “compatible” PLT
- HLA matched PLT
- Avoid HLA specificities based on Abs
- PLT XM
- Acceptable HLA mismatches
HLA & TRALI
- Transfusion Induced Lung Injury
- Donor’s blood has HNA, HLA I, HLA II
- Activate patient’s HLA activate neutrophils and endothelial cells
HLA Prevention
- Screen for HLA Abs only for female donor donating PLT and AB Plasma
- Donors positive for HLA Abs will be deferred forever
RBC Genotyping vs Phenotyping
- Genotype: RBC antigen predicted by DNA sequence at a particular location on chromosome
- Phenotype: RBC antigen expressed as determined with serologic method
Problems with serological typing
- Multiple RBC population
- Interfering Abs
- Discrepant results or undetectable underlying genetic differences in blood group Ag
- No antisera available
- No sample avaialble
Indications for RBC genotyping
- Post-transfusion
- Discrepant serologic results
- Unable to detect
- No antisera
- Interfering Abs
- No sample (fetus)
- Zygosity matters
- Desire to RBC type large number of people
Acute Immunologic TR
- During or w/in 24hrs of transfusion
- DAT positive
- Increase bilirubin; LDH;
- Decrease: hemoglobin, haptoglobin;
Acute Non-immunologic TR
- During or w/in 24hrs of transfusion
- DAT negative - Independent with Abs
- Asymptomatic; hemoglobinuria
- Caused by chemical or physical damage (improper shipping & storage)
Delay Immunologic TR
- After 24hrs
- AbSC switch from neg to pos
- If DAT positive, perform eluate –> Eluate positive —> Antigen typing units transfused.
- Other markers of hemolysis: LDH, Total bilirubin, direct bilirubin, haptoglobin
Delay Non-immunologic TR
- After 24hrs
- Independent with Abs
Why AHTR so dangerous
- Hypotension and shock
- Acute renal failure
- Disseminated coagulopathy and bleeding
4 most dangerous (to the health of the patient) transfusion reactions
- Acute hemolytic = intravascular hemolysis
- TRALI
- Bacterial contamination (RBCs)
- Anaphylaxis
Why Yersinia enterocolitica dangerous
- Cause RBC contaminated (grow in cold, love heme)
- Produce endotoxin
- Come from an asymptomatic donor
Organism assoc. with PLT contamination
S. aureus and S. epidermis
Methods to reduce the chance of bacterial contamination of platelets
- Diversion pouch to remove skin plug
- Bacterial detection test on all PLT
Report of transfusion-related deaths to FDA
Verbally report by e-mail as soon as possible and in writing by 7 days
