Air-drop blood supply in the French Army.

BACKGROUND: Haemorrhagic shock remains the leading cause of preventable death in overseas and austere settings. Transfusion of blood components is critical in the management of this kind of injury. For French naval and ground military units, this supply often takes too long considering the short shelf-life of red blood cell concentrates (RBCs) and the limited duration of transport in cooling containers (five to six days). Air-drop supply could be an alternative to overcome these difficulties on the condition that air-drop does not cause damage to blood units. METHODS: After a period of study and technical development of packaging, four air-drops at medium and high altitudes were performed with an aircraft of the French Air Force. After this, one air-drop was carried out at medium altitude with 10 RBCs and 10 French lyophilised plasma (FLYP). A second air-drop was performed with a soldier carrying one FLYP unit at 12 000 feet. For these air-drops real blood products were used, and quality control testing and temperature monitoring were performed. RESULTS: The temperatures inside the containers were within the normal ranges. Visual inspection indicated that transfusion packaging and dumped products did not undergo deterioration. The quality control data on RBCs and FLYP, including haemostasis, suggested no difference before and after air-drop. DISCUSSION: The operational implementation of the air-drop of blood products seems to be one of the solutions for the supply of blood products in military austere settings or far forward on battlefield, allowing safe and early transfusion.

Soluble Fc gamma receptors II (Fc gamma RII) are generated by cleavage of membrane Fc gamma RII.

This study describes the production of soluble Fc gamma RII by a cell line, D1B1, obtained by transfection of mouse L cells with a murine beta 1 Fc gamma RII cDNA. Upon incubation at 37 degrees C, radioiodinated D1B1 cells release a 39-kDa soluble Fc gamma RII, reacting with the rat anti-mouse Fc gamma RII monoclonal antibody 2.4G2, and binding to mouse IgG2a, IgG2b and IgG1 but not IgG3. In contrast to the transmembrane 50- to 70-kDa receptor, this soluble Fc gamma RII does not react with antibodies directed against a peptide corresponding to the 15 carboxy-terminal intracytoplasmic amino acids of beta Fc gamma RIII. N-Glycosidase F treatment generates a 18-kDa polypeptide. A 32- to 40-kDa soluble Fc gamma RII, which resolves into 18.5- and 20-kDa polypeptides after deglycosylation, was also isolated from the culture medium of unlabeled D1B1 cells. Therefore, this study indicates that soluble Fc gamma RII corresponding to the two extracellular domains of Fc gamma RII are generated by cleavage of membrane Fc gamma RII. Proteolysis occurs most probably at the vicinity of the transmembrane region of the receptor, around amino acids 165 to 180.

Recombinant soluble receptors for the Fc gamma portion inhibit antibody production in vitro.

The problem of the structural relationship between suppressive IgG-binding factor and low-affinity receptors for the Fc portion of IgG (Fc gamma RII) has not yet been solved. In the present work we have isolated a recombinant soluble Fc gamma RII containing only the two external domains of Fc gamma RII, and analyzed its biochemical characteristics and biological activity. A cDNA encoding Fc gamma RII was mutated by the creation of a stop codon at the Lys175 codon. L cells have been transfected with this cDNA inserted into an expression vector. A cell line was obtained that secretes recombinant soluble Fc gamma RII which reacts with a monoclonal anti-Fc gamma RII antibody and binds to IgG1, IgG2a and IgG2b murine isotypes but not to IgG3 or F(ab')2 fragments of IgG2a. The secreted molecule contains two molecular species of relative molecular mass (Mr) 44,000 and 34,000-38,000 and of pI 4.5 and 6.3. They correspond to different glycosylations of a single polypeptide of Mr 19,000. After purification to homogeneity, soluble Fc gamma RII has found to suppress secondary and primary in vitro antibody responses in a dose-dependent way. The present work shows that recombinant soluble Fc gamma RII has biochemical characteristics, immunoreactivity and biological activity similar to those of suppressive IgG-binding factor.

Methylation in the 5' region of the murine beta Fc gamma R gene regulates the expression of Fc gamma receptor II.

In order to identify possible mechanisms regulating the expression of Fc gamma RII, we have examined the methylation status of the beta Fc gamma R gene in a panel of Fc gamma RII (+) and (-) cells belonging to several different lineages. We used beta 1 cDNA probes, derived from beta Fc gamma R gene transcripts which encode murine Fc gamma RII molecules. We found that all CCGG sequences detected with these probes were methylated in the genomic DNA of the Fc gamma RII-(-) cells. By contrast, two CCGG sites were found to be selectively unmethylated in the DNA of all Fc gamma RII(+) cells tested. These sites could be assigned to the region of the 5' end of the beta Fc gamma R gene. Besides, the treatment of Fc gamma RII(-) thymoma cells BW5147 with 5-azacytidine induced a hypomethylation of the beta Fc gamma R gene concomitantly with the transcription of that gene as seen by Northern blotting and the expression of functional Fc gamma RII. Conversely, the DNA-methylating agent ethyl methanesulfonate completely reversed the phenotype of the 5-azacytidine-treated cells to that of the Fc gamma RII(-) BW5147 parent cells. In ethyl methanesulfonate-treated cells, the beta Fc gamma R gene was remethylated and the corresponding transcript was no more detectable. We conclude that the methylation of a specific 5' segment of the beta Fc gamma R gene regulates the expression of Fc gamma RII in murine T cells, B cells, mast cells, and macrophages, possibly by controlling the gene transcription.