6 of the 14 patient samples had a change in crossmatch reactivity and there was no commonality seen in either patient sample type or antibody present. Of the 6 that had a change in reactivity; 3 had HLA/Platelet antibody, 2 had HLA antibody only, 1 was antibody negative, 3 were serum patient samples and 3 were plasma patient samples. A decrease in reaction strength was seen in 9 out of 64 (14.1%) of pathogen reduced sample crossmatches, 5 of these reactions becoming negative. 1 pathogen reduced sample crossmatch reaction increased in strength.

Samples from 14 different patients were crossmatched, using Immucor Capture-P® , with between 3-8 SDP samples obtained prior to PI treatment. After PI treatment, a 2nd

sample was taken from each of the same SDP units and crossmatches were repeated. A total of 64 platelet crossmatches, inclusive of all patient samples, were performed using the samples collected prior to PI treatment and all 64 were repeated using post PI treatment samples. Reaction strength at crossmatch (graded as “+” strong positive, “w” weak positive and “0” negative) in the pre and post treatment SDP samples was compared. ABO of SDP was not a consideration in testing as only the crossmatch reaction strength was evaluated. Platelet antibody screen testing had previously been done on all 14 patient samples; 2 were positive for HLA antibody only, 8 were positive for both HLA and platelet antibody and 4 were negative for antibody. Both serum and plasma patient samples were included in the patient group used for crossmatching.

REFERENCES

1. Immucor Capture-P® Solid Phase System for the Detection of IgG Antibodies to Platelets package insert; version 340-14

INSERT TABLE/IMAGE CONTENT

INTRODUCTION/ABSTRACT

MATERIALS AND METHODS

RESULTS

CONCLUSIONS

Our laboratory uses a solid phase test system for platelet crossmatching. One of the stated limits of this platform is that chemical contamination of test material can cause erroneous test results. The units we use for platelet crossmatching are pulled from the general stock inventory and, if the original product sample in the lab is >24 hours old, a new product sample is taken at time of crossmatch testing. As the demand for pathogen reduced single donor platelets (SDP) increases, the percentage of pathogen reduced SDPs in general stock inventory will likely also increase thereby affecting the availability of non-pathogen reduced SDP units for crossmatching.

PLATELET CROSSMATCHING USING PATHOGEN REDUCED VS. NON-PATHOGEN REDUCED SINGLE DONOR PLATELETSKim Greco,1 Johnny Mercedes,1 Ellen Christenson,1 Sarai Paradiso,¹1 Core Operations, New York Blood Center, NY

Because the pathogen inactivation (PI) process we are using involves treatment of the SDP with a chemical agent, amotosalen, we wanted to determine if samples taken from pathogen reduced SDPs could be used for platelet crossmatching.

The crossmatch reaction strength of platelet samples can decrease when using SDP samples taken after pathogen inactivation treatment with amotosalen when using our crossmatching platform. Platelet crossmatching should only be performed on SDP samples taken prior to pathogen inactivation treatment for the most accurate results.

SDP product samples for testing are only viable for 24 hours in the tube. As a result, most SDPs that are crossmatched require a sample to be taken from the product at the time of testing. Because we have shown that samples take from SDPs that have undergone pathogen reduction using amotosalen are not suitable for platelet crossmatching using our testing platform, an increase in the production of pathogen inactivated products in inventory would decrease the number of units available to crossmatch. With fewer units available, finding compatible units for more difficult patients could become an issue. Finding methods to keep pre treatment product samples viable for testing, whether through additives or alternate storage, will be a focus for our lab going forward as the demand for PI platelets increases.

The clinical efficacy of platelets crossmatched using a post PI sample was not evaluated in this study but should be correlated in the future.

Potential impact on available units useable for crossmatching as PI production increases can be seen in redistribution of percentages of PI SDPs, SDPs for XM and total collection available to use for crossmatching. Data for Oct/18 – Dec/18 is projected based on monthly averages and reflect the acquisition of 1 new PI customer starting Oct/18.

OBJECTIVES Patient Antibody Result

Sample Type No. Units XM’d

Discrepancy between pre/post sample XM

results?

1 HLA/Plt Serum 3 No

2 HLA/Plt Plasma 8 Yes- (1) w+ to 0 and (1) + to w+

3 HLA/Plt Serum 3 No

4 HLA Plasma 4 Yes – (1) + to w+

5 HLA/Plt Serum 4 No

6 HLA/Plt Serum 4 Yes – (1) w+ to 0

7 Negative Serum 4 No

8 Negative Serum 4 No

9 HLA/Plt Serum 5 No

10 HLA/Plt Plasma 5 No

11 HLA/Plt Plasma 5 Yes – (1) w+ to 0, (1) + to w+ and (1) w+ to +

12 HLA Serum 5 Yes – (1) + to w+ and (2) w+ to 0

13 Negative Plasma 5 No

14 Negative Serum 5 Yes – (1) w+ to 0

Number of PI SDPs and SDPs used for crossmatch relative to the total collection by month. Projected data used for Oct/18 – Dec/18 based on past performance and current PI production projections.

I N N O VA T I O N � E X P E R I E N C E � E X P E R T I S E

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