Long-term in vitro reactivity for human leukocyte antigen antibodies and comparison of detection using serum versus plasma.
BACKGROUND
Human leukocyte antigen (HLA) antibodies are a possible cause of transfusion-related acute lung injury (TRALI), and fluorescent bead assays are often used for antibody detection. Serum is the manufacturer's recommended sample, but plasma may be easier to obtain for studies of HLA antibody prevalence and TRALI case investigations.


METHODS
Specimens were obtained from 44 multiparous females positive for the presence of HLA antibodies by lymphocytotoxicity testing at least 13 years prior and from 1000 contemporary blood donors. Screening tests were performed using a multiplex bead-based assay. In addition to comparing results obtained with paired plasma and serum samples, the effects of storage at 4 degrees C for 1 week and of multiple freeze-thaw cycles were evaluated.


RESULTS
Of 42 evaluable subjects with HLA antibodies documented more than 13 years earlier, only 1 showed loss of detectable antibodies, with 39 (93%) positive in the screening assay for HLA Class I and 24 (57%) positive in the screening assay for HLA Class II antibodies. In 968 evaluable contemporary donors, 291 screened positive for the presence of HLA Class I and 206 for HLA Class II antibodies using a low assay cutoff. Screening test concordance using paired plasma and serum samples was high, particularly for subjects with higher-level antibodies. Refrigeration of samples for 1 week did not significantly affect assay results, while repeated freeze-thaw cycles caused a decrement in signal level.


CONCLUSIONS
Serum and plasma samples gave concordant results in the majority of cases, particularly for specimens with higher-level antibodies. High-level HLA antibodies were present in most individuals for more than 13 years.
Norris
Philip J
PJ
Blood Systems Research Institute, University of California, San Francisco, USA. pnorris@bloodsystems.org
Lee
Jar-How
JH
Carrick
Danielle M
DM
Gottschall
Jerome L
JL
Lebedeva
Mila
M
de Castro
B R
BR
Kleinman
Steven H
SH
Busch
Michael P
MP
D055371:Acute Lung Injury / Q000209:etiology; D000906:Antibodies / Q000276:immunology*; D001782:Blood Donors; D015331:Cohort Studies; D003601:Cytotoxicity Tests, Immunologic; D005260:Female; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D010298:Parity; D010949:Plasma / Q000276:immunology*; D011247:Pregnancy; D015995:Prevalence; D015203:Reproducibility of Results; D044967:Serum / Q000276:immunology*; D013997:Time Factors; D014481:United States / Q000453:epidemiology
D000906:Antibodies; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II