engleski

Positive antibody test without detectable specific antibodies;part I:features

Methods:During 2002–2004 samples with positive antibody testsbut with no identified specific antibodies were investigated byrepeated screening/crossmatch, papainized panel identification, HLA antibody screening by lymphocytotoxicity test (LCT) andELISA in some cases. Patients’ age, sex, department, diagnosis, pre-vious transfusions/pregnancies, techniques, reactions’ strength, number of positive cells, urgency, subsequent antibody tests, iden-tification and LCT were noted. Antibody tests were performed: atpretransfusion testing (PT) by LISS-Coombs (DiaMed) and at bloodgrouping (BG) by BioVue polyspecific (Ortho) microcolumns – man-ually in urgency and routinely by Sampler IIF (DiaMed) and MITIS(Ortho) systems.Results:Investigated reactivity was recorded in 241 samples from186 patients ; 29 (15.6%) patients had >1 episode. These findingscomprised 15.1% of 1598 unexpected results found at PT and BG.Incidences were 0.18% at routine and 0.21% at urgent BG (37 339and 16 003 BGs, respectively), and 0.35% both at routine and urgentPT (15 803 and 23 705 PTs, respectively). 56.5% patients werefemale, 44.6% over 60, but 19.9% <30 years, coming mostly fromsurgery (19.4%), internal medicine (15.1%), hematology (10.8%), ginecology (10.2%), cardiac diseases (9.1%) and cardiac surgery(8.6% patients). Frequent diagnosis were solid tumors (16.1%), cardiac diseases (13.4%), hematologic malignancies (8.6%), uraemia(4.8%), orthopedic surgery (4.3%) and hepatic diseases (3.2%patients). 43.0% patients were previously transfused, with only 9.1%patients proved as not transfused or pregnant. Subsequently posi-tive antibody test during the study had 27.6% tested patients. AtPT positive crossmatch was found in 38.8%, antibody screening in43.9% and both tests in 17.3% cases. Majority of reactions were‘1+’ (50% at PT and 38.6% at BG) ; reactions ‘3+’ or ‘4+’ were foundin only 5.1% cases at PT, compared to 17% at BG. One crossmatchonly was positive in 75.2% positive crossmatches, with 38/43patients having >1 crossmatched unit. AHG identification was pos- itive in 27.6% tested patients ; in 26% of them papainized panel wasalso positive. Lymphocytotoxic antibodies were found in 45.5%tested patients ; 72.6% (8%–100%) of lymphocytes were reactive.Finally, the cause of reactivity in antibody tests was determined as‘laboratory mistake’ in 42.5%, HLA lymphocytotoxic antibodies in9.7%, ‘IgG antibodies of unknown specificity’ in 7.5% (HLA non-cytotoxic antibodies in 2/2 ELISA tested samples!), contaminatedsample in 5.9%, anti-Bga in 4.8%, non-specific cold antibodies in3.8%, subsequently recognized specific antibodies in 3.2% (2 Lua, 2M, 1 Kpa, 1 Yka), non-specific autoantibodies in 3.2%, carry-overof DAT-positive cells and antibody to reagent in 2.2% cases each, while in 4.3% cases antibody screening and in 4.8% cases cross-match was repeatedly positive without confirmation in panels.Discussion:After introducing of sensitive microcolumns, positiveantibody tests without detectable specific antibodies require sig-nificant laboratory activities, particularly in older patients withmalignancies or surgery. Such reactivity was frequently caused bylaboratory mistake, but often HLA and sometimes specific anti-bodies were later recognized, or reactivity continued without con-firmation in panels. Relationships that may be helpful are furtherdiscussed in abstract part II.

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