Monoclonal reagents for rhesus-D typing of Irish patients and donors: a review.

Polyclonal anti-D reagents have been largely replaced by monoclonal reagents; however, although generally very potent, they can exhibit some variation in activity, particularly in the detection of weak Rhesus (Rh) D-positive cells. Hence, although patients and donors previously typed as Rh-D-negative (Du positive) are now being typed as Rh-D-positive, it is likely that two monoclonal reagents selected for Rh-D typing may give anomalous results. This has led to confusion in testing patients and donors in Irish laboratories. To address this problem, 29 commercially available monoclonal and monoclonal/polyclonal anti-D reagents were evaluated for reactivity with partial D and efficiency of weak-D detection, using the manual tube technique. The anti-D reagents used in column technologies (Biovue and Diamed) also were evaluated. Testing was limited by the availability of partial-D cells. The reagents directly agglutinated the majority of partial-D cells, with the exception of DVI, which required the indirect antiglobulin test for detection. Totem (Diagast) and Z039 (Scottish National Blood Transfusion Service) both directly agglutinated DVI. The weak-D detection rate for a number of immunoglobulin M (IgM) reagents was improved by incubation of initially negative tests. Sedimentation techniques, recommended for a number of reagents, were unsuitable for weak-D or partial-D detection. There were indications that IgM/IgG reagents gave lower direct-agglutination weak-D detection rates than did IgM reagents, although Totem and Novaclone produced results matching those of the IgM reagents. Laboratories should be aware of the guidelines for Rh-D typing of patients and donors, and select anti-D reagents accordingly.