A murine monoclonal antibody has been produced (RFF-VIII:R/2) that binds specifically to human factor VIII-related antigen (VIII:RAg) in plasma and in vascular endothelial cells but has no reactivity with factor VIII procoagulant antigen (VIII:cAg). This antibody is a potent inhibitor of von Willebrand factor activity (VIII:vWF) in that it can totally neutralize ristocetin-induced aggregation of platelet rich plasma and inhibit platelet adhesion at high flow rates. RFF-VIII:R/2 can be used in a one-stage, fluid phase immunoradiometric assay that can detect VIII:RAg at concentrations of 0.001 u/ml. This method has been used to analyse plasma from patients with von Willebrand's disease (vWD). Results obtained in these patients showed a high degree of correlation between the monoclonally-defined epitope and VIII:vWF levels measured by ristocetin-induced aggregation of washed platelets. This correlation was maintained in those patients with the 'variant' types of vWD who exhibit highly disparate VIII:vWF and VIII:RAg levels when the latter is determined using polyclonal antisera. It appears that this monoclonal antibody recognizes a site on the VIII:RAg molecule which is associated with its interaction with the platelet membrane. Immunoradiometric assays using RFF-VIII:R/2 offer a simplified, reproducible means of detecting functionally-active VIII:RAg as an alternative or supplement to techniques involving platelet interactions.

The etiological relationship of infections to the diffuse form of acute and subacute nephritis is a problem which for many years has commanded attention, but has rarely received more than casuistic study.L6hlein (a) in 1907 described in detail the early lesions of the glomeruli in acute glomerular nephritis, as well as the subsequent changes that took place in the kidney during the subacute and chronic stages of the disease. Since a large proportion of his cases of acute and subacute nephritis occurred in patients suffering from various forms of infection, usually due to streptococci, he concluded that in the vast majority of cases acute glomerular nephritis was the direct result of streptococcus infection. Fahr (1912), somewhat later,pointed out the frequency with which acute glomerular nephritis was preceded or accompanied by infections particularly those due to streptococci, while Volhard and Fahr (1914) inflammation, it has been the idea of other observers (Schridde (1913)) that the diffuse lesions in the glomeruli are caused by the elimination of a toxin, produced by streptococci or by other bacteria in a focus of infection distant from the kidney.The demonstration by Dochez (1924) and by Dick and Dick (192 la) that a type of hemolytic streptococcus is the cause of scarlet fever adds fresh incentive to investigations on this problem, for the post scaratinal nephritis has always been considered as the prototype of the diffuse glomerular variety. The experiments, moreover, of Dick and Dick (1924b) on the elaboration of a filterable "toxin" by Streptococcus scarlatinae indicate still further methods which might be applicable to studies upon nephritis.It has seemed to us important to investigate two phases of the problem, first the relationship of acute infections to the onset of glomerular nephritis, and secondly the relation of infections to the progress of nephritis. If streptococcus infections of the upper respiratory tract, such as tonsillitis, sinusitis, etc., are directly responsible for the onset of glomerular nephritis, the progress of the disease might bear some relationship to the course of the infection. With the subsidence of the infection and disappearance of the infecting organism one might expect recovery from the nephritis, provided the kidney itself is not the seat of active bacterial growth; while progression of the nephritis to a subacute or chronic stage might be accompanied by persistence or exacerbations of the infection such as those of the upper respiratory tract, or at least by the continued presence of the infecting organism in these situations.With this idea in mind it has been possible to study forty cases of acute or subacute glomerular nephritis in young adults, and in twentyseven of these to follow the course of the disease with some care over a period varying from a few months to four years. Cases of focal nephritis occurring in bacterial endocarditis were excluded.The ages of the patients were as shown on page 4. Most patients were seen within a few days to a few weeks of th...

A murine hybridoma clone is described that grows continuously in culture and produces a monoclonal antibody we have called Royal Free Monoclonal Antibody to factor IX No. 1 (RFF-IX/1). This has high affinity for a coagulation site on factor IX. RFF-IX/1 immobilised on sepharose can be used to deplete factor IX from normal human plasma. This immunoaffinity depleted plasma is indistinguishable from severe Christmas disease plasma and can be used as the substrate in a one stage coagulation assay for factor IX. The affinity column has high capacity and can be regenerated so that large scale production from normal plasma of factor IX deficient plasma as a diagnostic reagent is now feasible.

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Summary These experiments show conclusively that guinea-pigs may be readily sensitized to extracts of horse dander that contain a total nitrogen content of approximately 40 mgm. per 100 cc., and that are preserved at a reaction of approximately pH 7.4. In many instances the sensitization may be of such comparatively high degree that 0.05 cc. of extract injected intravenously will cause characteristic anaphylactic death within three to four minutes, or that the uterine muscle of sensitized guinea-pigs in a Dale bath of 200 cc. of Locke's solution will contract promptly on the addition of from 0.01 to 0.001 cc. of extract. The sensitization is specific for the antigen or antigens that are contained in the extract of horse dander, for guinea-pigs sensitized to horse dander extract do not react to horse serum, while guinea-pigs sensitized to horse serum do not react to horse dander extract. When guinea-pigs highly sensitized to horse dander extract are injected intravenously with sublethal doses of the extract, they are desensitized twenty-four hours later to intravenous injections of many times the lethal dose of extract. Likewise the uteri of virgin guinea-pigs which have reacted to additions of small amounts of the extracts are insensitive to further additions of large amounts of the extract. It is possible to conclude, therefore, from these experiments that extracts of horse dander contain an antigen or antigens which give anaphylactic reactions in guinea-pigs that are precisely the same as the anaphylactic reactions produced by any one of a large number of proteins.