Defining capabilities in deployed UK military prehospital emergency care

The UK military prehospital emergency care (PHEC) operational clinical capability framework must be updated in order that it retains its use as a valid operational planning tool. Specific requirements include accurately defining the PHEC levels and the 'Medical Emergency Response Team' (MERT), while reinforcing PHEC as a specialist area of clinical practice that requires an assured set of competencies at all levels and mandatory clinical currency for vocational providers.A military PHEC review panel was convened by the Defence Consultant Advisor (DCA) for PHEC. Each PHEC level was reviewed and all issues which had, or could have arisen from the existing framework were discussed until agreement between the six members of this panel was established.An updated military PHEC framework has been produced by DCA PHEC, which defines the minimum requirements for each operational PHEC level. These definitions cover all PHEC providers, irrespective of professional background. The mandatory requirement for appropriate clinical exposure for vocational and specialist providers is emphasised. An updated definition of MERT has been agreed.This update provides clarity to the continually evolving domain of UK military PHEC. It sets out the PHEC provider requirements in order to be considered operationally deployable in a PHEC role. There are implications for training, manning and recruitment to meet these requirements, but the processes required to address these are already underway and well described elsewhere.

Requirement of the T cell receptor for antigen presentation by T lymphocytes. Effect of envelope glycoproteins of HIV-1 on antigen presentation by T cells

We have developed CD4+, tetanus antigen-specific T cell clones that proliferate in the presence of tetanus antigen and autologous irradiated peripheral blood leucocytes (PBL) as antigen-presenting cells (APC). There have been several reports that T cells can present antigen themselves. We have used tetanus antigen-specific T cell clones to examine the effects of envelope glycoproteins of HIV-1 on processing and presentation of antigen to T cells. Cloned T cells were pre-incubated with soluble crude preparation of tetanus antigen for 4 h at 37 degrees C, irradiated, and used as APC (T-APC). These cells could present antigen, as assessed by the ability of the autologous cloned T cells to proliferate. Resting T cells and phytohaemagglutinin-activated T cell blasts from autologous PBL could not present tetanus antigen to the responder cloned T cells. Antigen presentation by T-APC was abrogated by treating cells with anti-HLA-DR but not by anti-HLA-DQ monoclonal antibodies; treatment of tetanus antigen-pulsed T-APC with anti-tetanus antibody also blocked the ability of these cells to induce proliferation in responder T cells. Antigen presentation by cloned T cells was by a chloroquine-resistant pathway. Pretreatment of T-APC with envelope glycoprotein of HIV-1, gp120, did not affect the proliferative responses of the responder T cells. These data suggest that gp120 does not inhibit the antigen-presenting function while suppressing antigen-specific responses.

Recombinant interleukin 2 therapy in severe combined immunodeficiency disease

Severe combined immunodeficiency disease (SCID) is a congenital disorder of severe B- and T-lymphocyte dysfunction in which several pathogenic mechanisms have been identified. The present study describes a female child with SCID who had a primary defect in the ability of T cells to secrete interleukin 2 (IL-2). B- and T-cell numbers were normal, but their functions were severely deficient. Mitogen and antigen-driven lymphoproliferative responses were diminished but were correctable in vitro with recombinant IL-2 (rIL-2). The patient's phytohemagglutinin-stimulated lymphocytes expressed IL-2 receptors normally. Despite the presence of the gene for IL-2, the patient's cells were grossly deficient in messenger RNA for IL-2 and endogenous IL-2 production. Pokeweed mitogen-driven B-cell differentiation was decreased and was not corrected by the addition of normal T cells to the B cells. Two attempts at immune reconstitution by haploidentical bone marrow transplantation failed. Therapy with rIL-2 (30,000 units/kg, given daily i.v.) resulted in marked clinical improvement as well in improved T-cell functions. The child, now 3 yr old, has been on rIL-2 therapy for 2 yr and receives rIL-2 (30,000 units/kg) three times weekly at home. This case study points to a new direction in the treatment of such disorders with rIL-2.

Villus atrophy and crypt elongation in the small intestine of preruminant calves fed with heated soyabean flour or wheat gluten

Serial biopsies were removed from the jejunal mucosa of preruminant calves given single or multiple feeds containing heated soyabean flour or wheat gluten. Morphometric investigation using a microdissection technique revealed partial villus atrophy and crypt elongation. The first exposure to soyabean protein caused slight shortening of villi but after a succession of experimental feeds of heated soyabean flour or gluten, animals developed marked mucosal abnormalities and severe diarrhoea. Villus atrophy and crypt elongation were seen 24 hours after challenge with an experimental feed and restoration of normal morphology on a diet of milk alone took about 10 days. The data are discussed in relation to coeliac disease of man and the use of soya products in milk replacers for calves.

Milk protein immune complexes in the cow and calf

Immune complexes formed between IgG and the milk protein beta-lactoglobulin have detected in bovine colostrum and in the serum of young calves. Complexes were present in all calves studied and the data suggest that they were passively acquired during suckling. The complexes had a molecular weight of 185 000 strongly suggesting the molecular configuration Ab1Ag2. Their half-life in calf serum was 12-21 days. alpha-Lactalbumin was also detected in calf serum and appeared to be complexed in a similar way. Attempts to dissociate the complexes at low pH and by reduction and separation of IgG heavy and light chains led to the release of only a small percentage of complexed beta-lactoglobulin. The results suggest that transient autoimmunity to milk and the transfer of milk protein complexes from mother to young are normal events in cattle. An immunosuppressive role for the immune complexes in postulated.

The preparation and properties of folate-binding protein from cow's milk

An improved affinity-chromatographic method for the preparation of folate-binding protein from cow's milk is described. Under dissociating conditions the protein appeared homogeneous in the ultracentrifuge, with a molecular weight of 35 000 +/- 1500, but it was heterogeneous on electrophoresis and ion-exchange chromatography and evidently consisted of several glycoproteins with similar molecular weights that all bound folic acid. Overall, the protein contained a high proportion of half-cystine (18 residues/molecule) and 10.3% of carbohydrate. At saturation it bound approx. 1 mol of folate/mol of protein at pH 7.2. Equilibrium-dialysis measurements of the binding of folic acid and 5-methyltetrahydrofolate to the purified protein gave non-linear Scatchard plots, the shapes of which depended on pH. The results were interpreted in terms of ligand binding to a polymerizing system in which the affinity of ligand for monomer was greater than its affinity for polymer. When the protein concentration was similar to that in cow's milk, dissociation constants (Kd) for folate and 5-methyltetrahydrofolate were 3 nM and 5 nM respectively at pH 7.2 and 37 degrees C, whereas Kd for the binding of folate to monomer was about 50 pM. The properties of the binding protein are discussed in relation to its possible role in folate absorption in the gut.

Passage of ingested protein into the blood during gastrointestinal hypersensitivity reactions: experiments in the preruminant calf

Preruminant calves given a series of feeds of heated soya bean flour (HSF) frequently develop gastrointestinal hypersensitivity to soya bean antigens. The permeability of the intestinal mucosa of calves undergoing hypersensitivity reactions to ingested HSF has been assessed by feeding them milk and quantitating the leakage of beta-lactoglobulin into the blood. Maternal beta-lactoglobulin did not evoke an antibody response in calves. Therefore its detection in the serum was not influenced by immunological mechanisms that normally remove or exclude antigens from the circulation. In sensitized calves ingestion of HSF caused a dramatic increase in the permeability of the intestine to beta-lactoglobulin. The change was transitory and after 24 hr permeability had almost returned to normal. The mucosal barrier was not permanently damaged regardless of the number or the severity of the reactions experienced. Indomethacin was ineffective in counteracting permeability changes. A progressive increase in the sensitivity of the gut to soya bean antigens was accompanied by a rise in the titre of serum antibodies to soya bean proteins. Absorbed beta-lactoglobulin was present in the serum in its monomeric form only, and quickly disappeared from the circulation. In an enzyme immunoassay used to measure its concentration absorbed beta-lactoglobulin was indistinguishable from the native protein. These results suggest that measurement of intestinal permeability to macromolecules might be useful in the diagnosis of certain forms of food allergy in man.