Blood Donor Testing

Question 1

Infectious agents tested in the US

Answer 1

HBV, HCV
HIV 1/2/0
HTLV
Syphilis
West Nile Virus
Trypanosoma cruzi
Zika virus

Question 2

Collecting tubes for donor testing

Answer 2

• 3 lavender top EDTA:
  + HBV/HCV/HIV - NAT & WNV - NAT
  + ZIKAV - NAT
• 1 pink top EDTA:
  + ABO/Rh, Syphylis, CMV, AbSC

- 1 red top clot tube: 
 \+ HBs Ag, HBc Ab; HCV Ab
 \+ HIV Ab
 \+ HTLV Ab
 \+ T. cruzi Ab

Question 3

Donor Screening Test - Serologic

Answer 3

• ABO/Rh
• AbSC
• HBs Ag
• HBc Ab (IgM, IgG)
• HCV Ab
• HIV Ab 1/2/0
• HTLV Ab I/II
• Syphilis Ab (IgG)
• T. cruzi Ab (1 time in lifetime, the 1st donor)

Question 4

Donor Screening Test - Nucleic Acid test

Answer 4

• HBV DNA
• HCV RNA
• HIV - 1/2/0 RNA
• West Nile Virus RNA
• Zika Virus RNA

Question 5

Serologic Testing

Answer 5

• EIA or ELISA and ChLIA (higher sensitivity and specificity than EIA)
• If non-rxn –> Neg –> No evidence of infection
• If rxn –> Repeat duplicate on the same sample
  + Both neg –> Neg –> Unit labeled and released
  + One neg –> “repeatedly reactive” –> Discard and perform confirmatory test
• Test are highly sensitive –> may have false positive –> Need more specific testing to confirm true infection
• With RR, FDA requires further evaluations. Not permitted to be transfused regardless of the confirmatory test.

Question 6

Nucleic Acid testing (NAT)

Answer 6

• Screen donor for HIV, HCV RNA
• Extract from donor -> amplify target viral NA
• Test in minipools (MP-NAT) of donor plasma samples
  + MP negative –> all donor are negative
  + MP positive –> individual NAT (ID-NAT) is performed
  + ID-NAT is positive: no repeat test, discard sample and defer donor permanently

Question 7

NAT - Automated

Answer 7

• Multiplex assays for HIV, HBV, HCV in 1 reaction chamber
• Individual or pools of 6-16 donors
• PCR or TMA
• Shorten window periods
• If pool positive –> each donor tested –> donor is found, that serum must be tested separately for HIV, HBV, HCV to see which virus –> notify the donor

Question 8

ABO/Rh & AbSC for donor

Answer 8

• For every donor’s blood
• Rh negative –> perform weak D to confirm a true negative
• AbSC on serum via IAT

Question 9

Extend phenotyping

Answer 9

• Most significant Ag: Rh & Kell
• Automated typing
• Helpful for: more rapid ID & allocation of Ag-neg units. Prevention of alloimmunization in sickle cell patient

Question 10

Capture-R methodology

Answer 10

• Ag coated on wells
• Donor plasma/serum added –> Donor’s Ab bind to Ag
• Sensitized RBC added to wells
• Plate centrifuged at the end of incubation

Question 11

Bacterial testing on PLT

Answer 11

• Usually gram +
• PLT kept at RT
• Level of bacteria too low to detect after collection –> allow time to grow

Question 12

Shelf-life of PLT

Answer 12

• 5 days: 1 day of collecting, 1 day of culture (12-24hrs) –> only 3 days after release
• Mitigation strategy to extend from 5 to 7 days if tesed within 24 hours of infusion.
• Pathogen inactivation/reduction

Question 13

Additional test for CMV

Answer 13

• DNA virus, cause mild illness to immunocompetent and more severe for immunocompromised
• Majority of donor (50-80%) are seropositive for CMV
• Screening test: anti-CMV IgG and IgM
• Optional
• Indication: CMV-neg or CMV-safe
• CMV-safe = leukoreduction

Question 14

Requirement for release of allogenic units

Answer 14

• All infectious diseases are non-reactive –> label and released
• AbSC is positive but all other tests are non-reactive:
  + Label RBC only with white tag
  + Plasma can be discard