18.1 Reagent manufacture and reference preparations - Platelet immunology
18.1.1: HPA typing reagents
There are several human platelet antigen (HPA) genotyping and phenotyping techniques. The latter are generally based on the use of polyclonal HPA alloantibodies obtained from immunised donors or patients, or monoclonal antibodies. HPA typing techniques that do not require polyclonal antibodies derived from donors or patients are the techniques of choice.
HPA typing reagents prepared from human source material should comply with the guidelines in chapter 11.1.4.10. An instructions for use (IFU) sheet (package insert) should be prepared and supplied with antibody typing reagents. Information in the IFU should further indicate the immunoglobulin class of the antibodies and the presence of any other contaminating antibodies reactive by the recommended methods.
HPA typing reagents used in genomic DNA and polymerase chain reaction (PCR)-based techniques should comply with the guidelines in chapter 14.
18.1.2: Composition of platelet cell panel for HPA antibody detection
It is recommended that laboratories make all reasonable efforts to include cells in their panel that will aid the detection and identification of clinically significant HPA antibodies. The panel should consist of platelets typed at a minimum for HPA-1, -2, -3, -5 and -15 by validated HPA typing techniques. Ideally, the panel should contain platelets that are homozygous for HPA-1a, -1b, -2a, -2b, -3a, -3b, -5a, -5b, -15a and -15b and be from group O donors.
HPA typing of a platelet panel donor should be based on two concordant typing results using samples obtained on different occasions.
18.1.3: Selection of normal control sera
Normal control sera should be taken from non-transfused group AB male or ABO-compatible blood donors. The sera should be screened and found negative for platelet-reactive antibodies (e.g. clinically non-significant autoantibodies or EDTA-dependent antibodies are occasionally detected in apheresis donors).
An appropriate number of normal sera should be used so that a statistically relevant normal range in a given assay can be determined.
18.1.4: Selection of positive control sera
At least 1 positive control should be included in each assay. The selection and number of positive control sera will depend on the technique and the HPA type of the platelets being used.
In glycoprotein-specific assays, a positive control for each glycoprotein used should be included as a minimum.
18.1.5: Reference preparations
Sensitivity of techniques should be monitored on the basis of the inclusion of a 'weak positive' control. For anti-HPA-1a, -3a and -5b, the internal sensitivity control should be calibrated against the WHO International Reference Reagents for anti-HPA-1a (NIBSC code 05/106), anti-HPA-3a (NIBSC code 03/190), anti-HPA-5b (NIBSC code 99/666) ans anti-HPA-15b (NIBSC code 18/220) when diluted as instructed by the manufacturer.
In-house sensitivity standards, with similar reaction strengths to the above reagents, should be prepared for anti-HPA-1, -3 and -5, and, if possible, for anti-HPA-2 and -15 antibodies.
18.1.6: Quality control schemes
Laboratories should take part in regular external quality control exercises such as the UK National External Quality Assessment Scheme (NEQAS) for Histocompatibility and Immunogenetics schemes for HPA genotyping and HPA antibody detection/specification. Effective mechanisms should be in place to correct poor performance in the quality scheme.
18.1.7: Nomenclature
The current HPA nomenclature must be used for recording platelet-specific alloantigen and alloantibody specificities [Metcalfe, 2003].
See Tables 18.1.1 to 18.1.6 for details of each HPA system. Any subsequent additions can be found in the Human Platelet Antigen Database.
| Antigen | Original names | Glycoprotein | CD |
|---|---|---|---|
|
HPA-1a
|
Zwᵃ, PlA1 |
GPIIIa
|
CD61
|
|
HPA-1b
|
Zwᵇ, PlA2 |
Not applicable
|
Not applicable
|
| Antigen | Original names | Glycoprotein | CD |
|---|---|---|---|
|
HPA-2a
|
Koᵇ |
GPIb alpha
|
CD42b
|
|
HPA-2b
|
Koᵃ, Sibᵃ |
Not applicable
|
Not applicable
|
| Antigen | Original names | Glycoprotein | CD |
|---|---|---|---|
|
HPA-3a
|
Bakᵃ, Lekᵃ |
GPIIb
|
CD41
|
|
HPA-3b
|
Bakᵇ |
Not applicable
|
Not applicable
|
| Antigen | Original names | Glycoprotein | CD |
|---|---|---|---|
|
HPA-4a
|
Yukᵇ, Penᵃ |
GPIIIa
|
CD61
|
|
HPA-4b
|
Yukᵃ, Penᵇ |
Not applicable
|
Not applicable
|
| Antigen | Original names | Glycoprotein | CD |
|---|---|---|---|
|
HPA-5a
|
Brᵇ, Zavᵇ |
GPIa
|
CD49b
|
|
HPA-5b
|
Brᵃ, Zavᵃ, Hcᵃ |
Not applicable
|
Not applicable
|
|
HPA-6bw
|
Caᵃ, Tuᵃ |
GPIIIa
|
CD61
|
|
HPA-7bw
|
Moᵃ |
GPIIIa
|
CD61
|
|
HPA-8bw
|
Srᵃ |
GPIIIa
|
CD61
|
|
HPA-9bw
|
Maxᵃ |
GPIIb
|
CD41
|
|
HPA-10bw
|
Laᵃ |
GPIIIa
|
CD61
|
|
HPA-11bw
|
Groᵃ |
GPIIIa
|
CD61
|
|
HPA-12bw
|
Iyᵃ |
GPIb beta
|
CD42c
|
|
HPA-13bw
|
Sitᵃ |
GPIa
|
CD49b
|
|
HPA-14bw
|
Oeᵃ |
GPIIIa
|
CD61
|
| Antigen | Original names | Glycoprotein | CD |
|---|---|---|---|
|
HPA-15a
|
Govᵇ |
Not applicable
|
CD109
|
|
HPA-15b
|
Govᵃ |
Not applicable
|
Not applicable
|
|
HPA-16b
|
Duvᵃ |
GPIIIa
|
CD61
|
|
HPA-17b
|
Vaᵃ |
GPIIIa
|
CD61
|
|
HPA-18b
|
Cabᵃ |
GPIa
|
CD61
|
|
HPA-19b
|
Sta |
GPIIIa
|
CD61
|
|
HPA-20b
|
Kno |
GPIIb
|
CD41
|
|
HPA-21b
|
Nos |
GPIIIa
|
CD61
|
|
HPA-22b
|
Sey |
GPIIb
|
CD41
|
|
HPA-23b
|
Hug |
GPIIIa
|
CD61
|
|
HPA-24b
|
Cab2ᵃ⁺ |
GPIIb
|
CD41
|
|
HPA-25b
|
Swiᵃ |
GPIa
|
CD49b
|
|
HPA-26b
|
Secᵃ |
GPIIIa
|
CD61
|
|
HPA-27b
|
Cab3ᵃ⁺ |
GPIIb
|
CD41
|
|
HPA-28b
|
War |
GPIIb
|
CD41
|
|
HPA-29b
|
Khaᵇ |
GPIIIa
|
CD61
|
|
HPA-30b
|
Labᵃ |
GPIIb
|
CD41
|
|
HPA-31b
|
Cab4ᵇ |
GPIX
|
CD42a
|
|
HPA-32b
|
Domᵇ |
GPIIIa
|
CD61
|
|
HPA-33b
|
BIᵃ |
GPIIIa
|
CD61
|
|
HPA-34b
|
Bzhᵃ |
GPIIIa
|
CD61
|
|
HPA-35b
|
Efsᵃ |
GPIIIa
|
CD61
|
References
Metcalfe P, Watkins NA, Ouwehand WH, Kaplan C, Newman P, Kekomaki R, De Haas M, Aster R, Shibata Y, Smith J, Kiefel V, Santoso S. (2003). Nomenclature of Human Platelet Antigens. Vox Sanguinis, 85, 240–245. https://doi.org/10.1046/j.1423-0410.2003.00331.x
Last updated on 4 September 2023