Mapping IgE-binding epitopes of Ric c 1 and Ric c 3, allergens from Ricinus communis, by mast cell degranulation assay.

Ric c 1 and Ric c 3 are the major castor bean allergens. In order to identify continuous IgE-epitopes in Ric c 1 and Ric c 3, pools of sera from rats immunized with a pool of 2S albumin from these seeds, Ric c 1 and Ric c 3 overlapping synthetic peptides, were used to screen for IgE-binding epitopes. The allergenic properties were monitored by mast cell degranulation assays, histamine quantification and human-IgE binding. Large and small chains isolated from these proteins present allergenic properties. Four continuous epitopes were identified in Ric c 3 and two in Ric c 1. This knowledge may allow the induction of protective antibody responses to antagonize the IgE recognition.

A novel neutralizing monoclonal antibody against both ricin toxin A and ricin toxin B, and application of a rapid sandwich enzyme-linked immunosorbent assay.

Two strains of neutralizing monoclonal antibodies (MAbs) anti-ricin, both B chain and A chain, named 3D74 and 4C13, were generated efficiently. The two antibodies recognized different epitopes located in a separated toxin structure domain characterized by enzyme-linked immunosorbent assay (ELISA) and Western blotting. 3D74 recognized space conformation epitope, whereas 4C13 recognized linearity epitope of ricin. 4C13 possessed a novel neutralizing ability; the safe period for intraperitoneal injection of 100 microg of antibody was 30 min after intraperitoneal injection of 2 microg of ricin (10 times LD50). Using 3D74 and 4C13 as pair-matching antibodies, we established sandwich ELISA and rapid ELISA for detection of ricin. The detection sensitivities were 31.3 and 156 pg/ml, respectively. Rapid sandwich ELISA was sufficiently sensitive and was performed easily for ricin detection without any special instruments.

A novel recombinant vaccine which protects mice against ricin intoxication.

Ricin toxin (RT) is a plant-derived toxin of extraordinary toxicity; a single molecule successfully internalized into the cytoplasm of a cell is lethal for that cell. An estimated dose of 1-10 microg/kg is lethal to humans, making aerosolized ricin a potential agent for bioterrorism. Vaccination against ricin using either denatured toxin or its modified A chain subunit (RTA) has been successful in experimental animals but both vaccines have potential toxicities. Recombinant (r) RTA has not been evaluated as a vaccine. However, the advantage of such a vaccine is that these potential toxicities can be deleted by appropriate mutations. In this study we have generated three mutants and shown that two lack toxicity as compared to the wild type rRTA. These mutants induce protective humoral immune responses in mice. One or both should be considered for use in humans.

Long-lasting contact urticaria from castor bean.

Type I (immediate) and type IV (delayed) allergic reactions to castor bean developed in a stockroom worker in a coffee roasting plant. The exceptionally strong contact urticarial patch rest reaction persisted for more than 48 hours and was therefore called "long-lasting contact urticaria." Light and electron microscopic observations indicated that eosinophils and mast cells were activated and participated in patch test reactions, which include both type I and type IV allergic reactions. Although patch testing is an absolute prerequisite for an accurate diagnosis of delayed allergy, it should be stressed that skin tests should not be performed with castor bean because of its toxicity and potential danger.

Long-lasting contact urticaria. Type I and type IV allergy from castor bean and a hypothesis of systemic IgE-mediated allergic dermatitis.

A unique urticarial type I patch-test reaction to castor bean that persisted for more than 48 hours and was followed by a delayed type IV reaction is described. Immunohistochemical and electron microscopic observations indicated involvement of eosinophils and IgE receptors on Langerhans' cells. The authors present a scheme for the role of Langerhans' cells in skin allergy.

Mean wheal diameter in skin tests for castor bean extracts in castor bean allergic workers of eastern Sudan.

The mean wheal diameter by prick test for castor bean (Ricinus communis, Euphorbiaceae) extracts was measured in a castor bean allergic population. Three types of castor bean extracts namely Cimmaron, Pacific and dust (a mixture of Cimmaron, Pacific and hull), were applied at 1/10,000 dilutions with a control solution. The subjects comprised 318 male workers who were divided into four groups with a fifth control group of 63 male workers. The solutions were tested on three subject groups with Cimmaron in the first, Pacific in the second, and dust in the third. All three extracts were applied in the fourth and the control groups. The results have shown that the Cimmaron type gives a larger wheal diameter than Pacific or dust at the same concentration. There were statistically significant differences between the wheal diameters caused by different extracts in the same subjects. The possibility of producing a type of seed containing less amount of allergen could be considered and experimented on by the agricultural research bodies.

Allergy to castor bean. I. Its relationship to sensitization to common inhalant allergens (atopy).

The IgE response to castor bean (Ricinus communis) was studied in 96 castor bean-allergic patients from Marseilles, France. All had positive skin tests to castor bean. The IgE response to grass, cat, dust mite, olive, and Parietaria was also measured, and a positive RAST to one or more of these allergens was taken to indicate atopic status. Castor bean-specific IgE antibodies, measured by RAST, were found in 87 (91%) of the castor bean-allergic patients, in two of 13 atopic Marseilles residents living close to the castor bean mills, in three of 42 allergic subjects who had no known contact with castor bean, and in none of a control group of 111 Marseilles blood donors. Very high levels of castor bean-specific IgE (maximum class 4 readings on the Phadebas RAST score) were found in 54 (56%) of the castor bean-allergic patients, but the level of IgE antibody to castor bean was not significantly different in atopic and nonatopic subjects. The frequency of a positive serological test (RAST) for atopy in castor bean-allergic subjects (32%) was very similar to that found in the local population (36%). These data indicate that castor bean is an extremely potent sensitizer for both atopic and nonatopic individuals. The magnitude of the specific IgE antibody response is not related to the atopic status of the patient and may be a function of the physiochemical characteristics of the allergen itself.

Allergy to castor bean. II. Identification of the major allergens in castor bean seeds.

Castor bean proteins were separated and identified by isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis and blotted onto nitrocellulose paper. The capacity of the castor bean proteins to bind human IgE was probed with sera from castor bean-sensitive patients and radiolabeled anti-IgE. It proved difficult to identify allergens with isoelectric focusing. However, three allergens were identified when proteins were first separated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis: the 2S storage albumin, the 11S crystalloid proteins, and a third protein doublet with molecular weights of 47 and 51 kd. Specific IgE antibody to the 2S storage albumin, measured by RAST, was detected in most (96%) castor bean-sensitive patients, confirming it as the major allergen. We would like to suggest that the 2S albumin be named Ric c I, that the crystalloid proteins be named Ric c II, and that the 47/51 kd doublet be named allergen 3.

Identification of the normal microglial population in human and rodent nervous tissue using lectin-histochemistry.

Mistletoe lectin-1 (ML-1) and Ricinus communis agglutinin-120 (RCA-1) both possess D-galactose-specific surface-binding sites. They were used to selectively identify microglial populations in aldehyde-fixed normal brain tissue by lectin immunohistochemistry on paraffin and frozen sections. Mistletoe lectin-1 was superior to RCA-1 in labelling microglia in the rat brain, whereas RCA-1 labelled human microglia better than ML-1. Thus, RCA-1 and ML-1 supplement each other for identifying microglial in human and rodent central nervous system tissues. The high reproducibility of the results and the applicability of the technique to routine histology, using formalin-fixed tissue, should facilitate study of the histogenesis and role of microglia in the CNS.

Sensitization to green coffee bean (GCB) and castor bean (CB) allergens among dock workers.

Dock workers (n = 218) occupationally exposed to green coffee beans (GCB) were studied, using a specific questionnaire for allergic symptoms and skin tests for common and occupational allergens. Thirty-one workers (14.3%) complained of allergic symptoms of the eye, nose and bronchial system at the workplace. The prick tests, using both commercial allergens and specific extracts prepared from the most common types of coffee and their corresponding sacks, confirmed a sensitization in 21 workers (9.6%). A positive skin reaction to castor beans (CB) was found in nearly all these cases; in ten workers there was also a positive reaction to GCB allergens and in 14 cases prick tests were positive to extracts of sacks. There was a good concordance between prick tests and specific IgE for CB (95.0%) and also, but to a lesser extent, for GCB. The authors concluded that there is a significant risk of sensitization to CB and GCB allergens in dock workers occupied in handling green coffee bean, despite the fact that the exposure is not continuous. CB emerged as a common contaminant of GCB from various countries. For effective prevention, a modification of the methods of transport is required to avoid CB contamination to other products. Eliminating environmental dust during shipping operations is the most important preventive measure and it can be achieved by the use of containers, as some exporting countries are already doing.

Human castor bean allergy and HLA-A, B, C, DR.

Our results in 27 castor bean-allergic patients typed for HLA-A, B, C, DR antigens show (although the observed difference did not reach a statistical significance after correction for the number of tested specificities) an increase of A2 cross-reacting group antigens and, on the other hand, of HLA-A29, B39, CW2, B12, DR2, and especially DR5 (48.1% vs. 26.9% - chi 2 = 5.579; uncorrected p: 0.01 less than p less than 0.02), which possibly participate in haplotypic combinations. The facts that the markers of the haplotype segments involved are more frequent in northern European populations (e.g., A3,B7--Scandinavian; A29,B12--English) and that regional haplotypes are decreased (e.g., A11,B35) suggest that the allergics could in some geographical areas be less genetically adapted to their environment. In the same way, the fact that although the global number of assigned HLA antigens was increased, the percentage of only some alleles (among these those belonging to the A2-CREG) was increased suggests not only a recessive model but a diminution of the polymorphism in allergics. This is in agreement with the physiological role of the HLA system, the polymorphism of which, according to the numerous restriction phenomena allowed at the cellular level, represents broad possibilities of adapted immune response in man. In any event, these findings clearly suggest that HLA-DR5 and B39 may be the markers of castor bean allergy in the Mediterranean area, to which are superimposed the HLA alleles linked to the general atopic susceptibility.

The relationship between total serum IgE and castor-bean-specific IgE antibodies in castor-bean-sensitive patients from Marseilles.

The relationship between serum IgE and castor bean (Ricinus communis)-specific IgE was studied in a group of dockworkers and other residents of Marseilles who were diagnosed as having castor bean allergy. The diagnosis was made because they had asthma or other allergic symptoms together with a positive skin test to castor bean. Total serum IgE was found to be higher in castor-bean-allergic patients (mean = 174 IU/ml) than in a control group of local blood donors (mean = 66 IU/ml). IgE levels were not as high as those found in the sera of a previously identified group of castor-bean-allergic dockworkers from Port Sudan (mean = 902 IU/ml). Castor-bean-specific IgE was demonstrated in the serum of 91% of the allergic group and there was some correlation with total IgE (r = 0.53, p less than 0.01). The proportion of IgE antibody specific for castor bean was determined in 20 castor-bean-sensitive patients using the radioallergosorbent test and was found to vary between 9 and 64% (mean = 38% or 265 ng/ml). No castor-bean-specific IgE antibody was detected in the control group.

Results of skin test and RAST in allergy to a clinically potent allergen (castor bean).

In order to investigate once more the usefulness of the RAST procedure in the diagnosis of reaginic hypersensitivity, we studied a series of patients showing a well known sensitivity to castor bean, which is a potent antigen, and compared the results with those given by patients with no clinical allergy to this antigen as confirmed by negative skin testing. The latter group included patients with no contact, a remote contact or a close contact with castor bean. Castor bean allergy seems to be a good model in the testing of human reaginic hypersensitivity. We observed in the castor bean positive group of forty-one patients a 95% correlation between RAST positivity and skin test positivity with only two negative RAST scores, and in the castor bean negative group of ninety-four patients, a 97% correlation, with three RAST positive scores. For its specificity and its good sensibility (although lesser than skin testing), RAST can thus be recommended as a diagnostic tool as a complement to skin testing. Moreover, for potent allergens, RAST offers a risk-free diagnostic alternative.

Asthma in merchant seamen and laboratory workers caused by allergy to castor beans: analysis of allergens.

Three merchant seamen and two laboratory workers who developed allergic symptoms following exposure to castor beans have been investigated. Bronchial-provocation testing with castor beans in the merchant seamen demonstrated a late reaction in two. Specific IgE against whole castor-bean extract and ricin, ricinus agglutinin and dericinated extracts of castor bean were found in the patients' sera using radioallergosorbent tests (RAST). RAST inhibition, toxocological and haemagglutination tests suggest that the ricin and dericinated extracts contain distinct allergens.

Castor bean allergy among workers in the felt industry.

We describe occupational allergy to castor bean in workers in a felt manufacturing plant. Twenty-six (37%) of the workers complained they were affected by the felt and were examined by us. Of these, 12 were considered to have occupational allergy. These 12 subjects had raised specific IgE levels to both felt and castor bean extracts. In addition, three subjects without occupational allergy had raised specific IgE. The presence of castor bean allergens in the felt was suggested by the correlation between the RAST scores to the felt and castor bean and confirmed by RAST inhibition experiments. The RAST results correlated well with the results of skin prick tests to felt and castor bean extracts. In addition it was found that atopy did not predispose the workers to castor bean allergy.