Extended phenotyping does not preclude the occurrence of delayed haemolytic transfusion reactions in sickle cell disease

Delayed haemolytic transfusion reaction (DHTR) is a potentially life-threatening complication of red blood cell (RBC) transfusions in sickle cell disease (SCD) and is classically induced by reactivation of previously formed antibodies. Improved antigenic matching has reduced alloimmunization and may reduce DHTR risk. We conducted a retrospective cohort study to investigate the incidence rate of DHTR in SCD patients receiving extended matched units (ABO/RhDCcEe/K/Fy^a /Jk^b /S). Occasional transfusion episodes (OTE) between 2011 and 2020 were reviewed for occurrence of DHTR symptoms using four screening criteria: decreased Hb, increased lactate dehydrogenase (LDH), pain, and dark urine. We included 205 patients who received a cumulative number of 580 transfusion episodes of 1866 RBC units. During follow-up, 10 DHTR events were observed. The incidence rate of DHTR was 13·8/1000 OTEs [95% confidence interval (CI): 7·37-22·2], with a cumulative incidence of 15·2% (95% CI: 8·4-24·0%) after 25 patients having received RBC units. One DHTR event was fatal (10%). Symptoms were misdiagnosed in four DHTR events (40%) as other acute SCD complications. Despite a lower incidence rate compared to most other studies, the incidence rate of DHTR in SCD remains high, in spite of extended matching of donor RBCs. Increased awareness of DHTR is of utmost importance to facilitate early diagnosis and, consequently, improve outcome.

Quantitative and qualitative analysis of haemoglobin variants using capillary zone electrophoresis

Capillary zone electrophoresis (CZE) has been introduced into the clinical chemistry laboratory because of its range of potential applications. In this paper, we evaluate an alkaline CZE method for the quantification of HbA2 and HbF and also assess the combination of the alkaline CZE method with an acid CZE method for the determination of haemoglobin variants in an automated fashion. Correlation of the HbA2% determined between the HbA2-CZE method (alkaline conditions) and the Helena Sickle Thal Quick Column method was good (r = 0.91). The correlation between the HbF% determined by the HbA2-CZE method and by the alkaline denaturation method was acceptable (r = 0.81). The HbA2-CZE method was able to identify a large number of haemoglobin variants. The variants HbC and HbE or HbS and HbD, however, had the same characteristics under alkaline conditions and could therefore not be discriminated from each other. The identification of these overlapping variants could be accomplished by the analysis of the blood specimens in combination with the HbA1c-CZE method (acid conditions). We conclude that the presented applications for capillary zone electrophoresis can be used for quantitative and qualitative analysis of haemoglobin variants.

Problem-based learning for tuberculosis and leprosy supervisors

A problem-based learning programme for tuberculosis and leprosy supervisors is reported from Nigeria. It proved stimulating, motivating and enjoyable, and encouraged independent learning. The quality of their subsequent field work was average to good and showed sustained motivation.

Localization and functional analysis of DNase-I-hypersensitive sites in the human c-sis/PDGF-B gene transcription unit and its flanking regions

We studied the regulation of the expression of the human c-sis/PDGF-B gene in the following panel of cell lines: K562 cells, in which expression is inducible by phorbol esters; cytotrophoblast-derived cell lines JEG-3 and JAR; carcinoma-derived cell lines PC3, T24 and HeLa, which show extensive differences in c-sis mRNA content; dermal fibroblasts, which do not express the gene. We demonstrate that the wide variety of levels of c-sis mRNA in these cells is mainly determined at the transcription level. Extensive gene rearrangements or amplifications, or significant differences in the stability of the c-sis transcript could not be found. In fibroblasts and placenta cell lines, inaccessibility of the c-sis promoter, rather than the absence of transcription factors that activate it, inhibits expression of the endogenous gene. Examination of the chromatin structure of the transcription unit and immediate flanking regions revealed several cell-type-specific DNase-I-hypersensitivity (DH) sites. Functional analysis of genomic fragments harbouring one or more DH sites showed the presence of negative regulatory elements within intron 1, and of an activating element downstream of the gene. A DH site, located immediately downstream of the promoter in dermal fibroblasts, may regulate accessibility of the promoter by means of specific nucleosome phasing.