Red Blood Cell Alloantibody Titration - Does the Titration Method Matter?

BACKGROUND: Red blood cell (RBC) alloantibody titration is a quasi-quantitative method to assess antibody concentration and is considered a useful means of estimating maternal alloimmunization during pregnancy. Traditionally, titration is performed using conventional tube test (CTT). The gel microcolumn agglutination-based method (GMA) has been proven reliable for many immunohematology tests. Our study compared CTT with GMA of two different, commercially available GMA systems for RBC alloantibody titration. METHODS: Serum samples with significant RBC-alloantibodies were evaluated in our study. Each sample was titrated concurrently with CTT, with ID-DiaMed-GmbH, Cressier, Switzerland (GMA1), and with DG Gel Coombs Diagnostic Grifols, Passeig Fluvial, Spain (GMA2). RESULTS: One hundred thirty-seven titration tests including 50 anti-D, 25 anti-Kell, 10 anti-E, 9 anti-Jka, 8 anti-c, 5 anti-Cw, 5 anti-Fya, 7 anti-M, 6 anti-Kpa, 3 anti-Lua, 1 anti-e, 3 anti-G, and 2 anti-Cha were performed and evaluated. Samples tested by CTT versus GMA1 and GMA2 generated mostly equal or higher titers by GMAs. The results of both comparisons were in good agreement (W = 0.91, p < 0.0001, and W = 0.92, p < 0.0001, respectively). For all antibody specificities, the mean absolute difference in titers ranged from 1 - 3 for both GMA1 and GMA2 versus CTT. Samples tested by GMA1 vs. GMA2 were in almost perfect agreement (W = 0.95, p < 0.0001). CONCLUSIONS: Although both GMAs were found slightly more sensitive than CTT for alloantibody titration, the differences were not significant and the agreement between all methods was very good, possibly indicating GMA as a suitable alternative to CTT in RBC antibody titration.

The effect of transfusion on immune responses in thalassemia.

BACKGROUND: Regular transfusions are the gold standard therapy for ß-thalassemia and are often complicated by secondary-iron overload and alloimmunization. We assessed the frequency of regulatory T cells (Tregs) and the levels of cytokines implicated in Th-responses in 49 patients 33 TDT and 16 NTDT in order to investigate the contribution of transfusion and its complications on immune responses. MATERIALS AND METHODS: Tregs were characterized with flow cytometry. Soluble IL-4, IL-6, IL-10, IL-17A, and TGF-ß1 were assessed by ELISA. Clinical data including alloimmunization, age of onset of transfusion splenectomy hepatitis B and C infection, iron overload assessment with MRI T2* (liver and heart) were recorded from the patients' files. RESULTS: Tregs levels, IL-6, IL-10, TGFß and serum ferritin were higher in the TDT compared to the NTDT group (all p < 0.05). There was no difference of Tregs and circulating cytokines in patients in correlation with the extend of iron overload (assessed by T2*liver), the type of chelator or the development of alloantibodies. DISCUSSION: Tregs levels are higher in TDT patients compared to NTDT, a difference which could be ascribed to transfusion. Tregs levels and the cytokines analyzed may play little role in alloimmunization and are not impacted by the extend of iron overload.

Variation of endothelium-related hemostatic factors during sepsis.

OBJECTIVE: The thrombomodulin/protein C and VWF/ADAMTS-13 pathways are disturbed in sepsis and have been implicated in the coagulation disorders that characterize the septic syndrome. We aimed to assess the variation of these endothelial parameters during sepsis and their putative association with outcome, in critically ill, septic patients. METHODS: We monitored 34 septic patients, 23 of whom improved (group A) while 11 deteriorated (group B). We assessed ADAMTS-13 levels, VWF activity, soluble thrombomodulin, and protein C activity upon admission to the ICU (time point 0) and at the time of a change in the clinical condition (remission or deterioration, time point 1). RESULTS: In group A, thrombomodulin and VWF increased at time point 1 compared to time point 0 (P = 0.011, P = 0.028, respectively). In group B, protein C and ADAMTS-13 significantly decreased (P = 0.023, P = 0.026, respectively), while VWF, VWF/ADAMTS-13 ratio, and the thrombomodulin/protein C ratio increased (P = 0.02, P = 0.002, P = 0.01, respectively). Protein C (> or ≤17%) and ADAMTS-13 percentage difference (> or ≤22%) were independently associated with sepsis outcome among the endothelial variables tested. CONCLUSIONS: An ongoing endothelial/hemostatic disorder was established during sepsis, observed even at clinical improvement. Among the variables tested, protein C and ADAMTS-13 change were associated with outcome.