An exploration of the advantages of automated titration testing: low inter-instrument variability and equivalent accuracy for ABO and non-ABO antibody titres relative to tube testing.

BACKGROUND AND OBJECTIVES: Obtaining IgM and IgG titres is important in numerous clinical situations, including solid-organ transplant, obstetrics, and for testing of out-of-group plasma-containing components. Tube method is the most prevalent testing modality, though it is both labour-intensive and known for intra- and inter-laboratory variability. The utility of automated gel testing as a method to improve both inter- and intra-laboratory reproducibility is unknown. MATERIALS AND METHODS: Two academic centres participated in a study evaluating automated gel titreing. Group O plasma samples were used to measure titres of antibodies against ABO (IgM) with buffered gel cards and 4 minor and minor red-blood-cell antigens (IgG) anti-IgG gel cards. Multiple ORTHO VISION automated analyzers were used to assess inter-instrument variation. A subset of ABO (IgM) samples were compared between laboratories to evaluate inter-laboratory variability. Multiple samples were titred by tube and by automated gel technology to determine similarity of results. RESULTS: Testing demonstrated no significant difference between analysers or between sites when performing automated titrations (P ≥ 0·99). Non-ABO IgG titres were evaluated and demonstrated little inter-instrument variability. The IgM anti-A and -B titres obtained by automated gel testing were neither consistently higher nor lower than tube titres. Greater than 90% of titre values were within one dilution. CONCLUSION: Based on this study, our data suggest that titreing by automated gel testing is both highly reproducible (IgM and IgG) and does not differ significantly from manual tube testing results of direct agglutination (IgM).

Successful treatment of pure red cell aplasia because of ABO major mismatched stem cell transplant.

BACKGROUND: Pure red cell aplasia (PRCA) is a well-documented potential side effect of ABO major mismatched allogeneic hematopoietic stem cell transplants. This side effect may be self-limiting, but is sometimes treated using modalities such as steroids, antithymocyte globulin, donor lymphocyte infusions, rituximab, or plasma exchanges. Another well-documented cause of pure red cell aplasia is a chronic parvovirus B19 infection, which may be seen in immunocompromised hosts. The treatment of this cause of PRCA includes removal of immunosuppression, intravenous immunoglobulin (IVIg), or rituximab; however, this condition may also be self-limiting. CASE REPORT: We show a case of a patient with PRCA who had previously received an ABO major mismatched allogeneic hematopoietic stem cell transplant, but also had an identified source of parvovirus B19 in his marrow post-transplant. RESULTS: He underwent several various treatments for his PRCA, including rituximab, bortezomib, and then plasma exchange. Anti-A IgM and IgG titers were drawn throughout his treatment course, and fell from 512 (anti-A IgM) and 1024 (anti-A IgG) to 2 (anti-A IgM) and 8 (anti-A IgG). After his last plasma exchange procedure, the patient's hemoglobin and reticulocyte count rose from 6.6 g/dL and 12.5 × 109 /L (respectively) at the onset of the PRCA diagnosis to 9.6 g/dL and 138.1 × 109 /L after a series of 14 plasma exchanges. CONCLUSION: This demonstrates a case of PRCA caused by an ABO major mismatched allogeneic hematopoietic stem cell transplant that was potentially complicated by a parvovirus infection, which was treated with multiple therapeutic interventions including a series of therapeutic plasma exchanges, rituximab, and bortezomib. Successful resolution of the patient's PRCA was achieved.