[Transfusion management and immuno-hematological follow-up after allogeneic hematopoietic cell transplantation: Guidelines from the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC)]

The French High Authority of Health (HAS) and National Drug Safety (ANSM) agencies recommendations issued in 2014, the French General Direction of Health (DGS) instruction published in November 2021, the French National Blood Bank (EFS) guidelines and the data available in the literature globally define "good transfusion practices" but provide little information about the immuno-hematological and transfusion management of patients who have received an allogeneic hematopoietic stem transplantation (allo-HCT). The aim of this workshop was to harmonize these practices in situations for which there are currently no recommendations. In order to anticipate possible transfusion issues after allo-HCT, we recommend performing, before the transplantation, an extended red blood cell phenotyping of the donor and a detection of HLA alloimmunization in the recipient. We recommend to systematically perform for minor ABO mismatches: a direct antiglobulin test between D8 and D20, and for major ABO mismatches; a titration of anti-A/anti-B antibodies and an erythrocyte chimerism at D100. At one-year post-transplant, we recommend carrying out an erythrocyte chimerism to allow, if necessary, the update of transfusion counselling (RH phenotype, irradiation of packed red blood cells).

[Study of four kits used for titration of tetanus antibody for selection of plasma donors intended to fractionation]

Antitetanus antibodies titration is carried out by French National Blood Services (FNBSs) with the aim of seeking donors whose title of antibodies are greater or equal to 8 IU/ml. Different kits are used: ELISA antitetanus toxoid IgG (The Binding Site), ELISAT (Diagast), tetanus toxoid IgG ELISA (Diamed), ELISA IgG tetanus (Ingen). As the results obtained using these different reagents show some discrepancies with the control results carried out by the Laboratoire Français des Biotechnologies (LFB), it appeared necessary to harmonize the selection practices. With this intention a study of the different kits was initiated.

METHOD

Different samples were used during this evaluation: (1) the Reference Control (RC) used by the FNBS; (2) a serum sample of high title; (3) a range of dilution of national standard. The following tests were carried out: (1) robustness with the evaluation of the contamination and the board effect; (2) linearity and repeatability (eight deposits of each standard, RC and points of national standard dilutions); (3) reproducibility; (4) homogeneity. After automatic dilution of the samples, the plates were then processed according to the protocol of the manufacturer.

RESULTS

The study gives the CV in percentage of repeatability and reproducibility, the values of the standards provided as well as the bias compared to the RC and the uncertainty of measurements.

CONCLUSION

This study gave the possibility to rank each kit compared to RC and to specify the variations which surround each result. This variation can explain the discrepancy of conformity of plasma when title is close to the threshold of selection.

The sulphonylurea glibenclamide inhibits multidrug resistance protein (MRP1) activity in human lung cancer cells

1. Glibenclamide, a sulphonylurea widely used for the treatment of non-insulin-dependent diabetes mellitus, has been shown to inhibit the activities of various ATP-binding cassette (ABC) transporters. In the present study, its effects towards multidrug resistance protein 1 (MRP1), an ABC efflux pump conferring multidrug resistance and handling organic anions, were investigated. 2. Intracellular accumulation of calcein, an anionic dye substrate for MRP1, was strongly increased by glibenclamide in a dose-dependent manner in MRP1-overexpressing lung tumour GLC4/Sb30 cells through inhibition of MRP1-related calcein efflux. By contrast, glibenclamide did not alter calcein levels in parental control GLC4 cells. Another sulphonylurea, tolbutamide, was however without effect on calcein accumulation in both GLC4/Sb30 and GLC4 cells. 3. Glibenclamide used at 12.5 microM was, moreover, found to strongly enhance the sensitivity of GLC4/Sb30 cells towards vincristine, an anticancer drug handled by MRP1. 4. Efflux of carboxy-2',7'-dichlorofluorescein, an anionic dye handled by the ABC transporter MRP2 sharing numerous substrates with MRP1 and expressed at high levels in liver, was also strongly inhibited by glibenclamide in isolated rat hepatocytes. 5. In summary, glibenclamide reversed MRP1-mediated drug resistance likely through inhibiting MRP1 activity and blocked organic anion efflux from MRP2-expressing hepatocytes. Such effects associated with the known inhibitory properties of glibenclamide towards various others ABC proteins suggest that this sulphonylurea is a general inhibitor of ABC transporters.

Reversal of MRP-mediated multidrug resistance in human lung cancer cells by the antiprogestatin drug RU486

Multidrug resistance-associated protein (MRP) and P-glycoprotein (P-gp) are drug efflux pumps conferring multidrug resistance to tumor cells. RU486, an antiprogestatin drug known to inhibit P-gp function, was examined for its effect on MRP activity in MRP-overexpressing lung tumor GLC4/Sb30 cells. In such cells, the antihormone compound was found to increase intracellular accumulation of calcein, a fluorescent compound transported by MRP, in a dose-dependent manner, through inhibition of cellular export of the dye; in contrast, it did not alter calcein levels in parental GLC4 cells. RU486, when used at 10 microM, a concentration close to plasma concentrations achievable in humans, strongly enhanced the sensitivity of GLC4/Sb30 cells towards two known cytotoxic substrates of MRP, the anticancer drug vincristine and the heavy metal salt potassium antimonyl tartrate. Vincristine accumulation levels were moreover up-regulated in RU486-treated GLC4/Sb30 cells. In addition, such cells were demonstrated to display reduced cellular levels of glutathione which is required for MRP-mediated transport of some anticancer drugs. These findings therefore demonstrate that RU486 can down-modulate MRP-mediated drug resistance, in addition to that linked to P-gp, through inhibition of MRP function.