Biomedical subjects
Publications and source records attributed to Donald R Hoffman.
Hymenoptera venoms each contain a variety of protein allergens. The major components have all been characterized, and most of the amino acid sequences are known. This article concentrates on the use of contemporary techniques including cloning, mass spectrometry and genomics in the characterization of venom allergens, and newer separation techniques for protein isolation. Examples of the use of these techniques with venom proteins are presented.
BACKGROUND: Sol i 1, the venom phospholipase of imported fire ant venom is an important allergen and exhibits some cross-reactivity with IgE antibodies from patients sensitized to other Hymenoptera venoms. OBJECTIVE: To determine the primary structure of Sol i 1 and evaluate the roles of protein and carbohydrate epitopes in its cross-reactivity. METHODS: Sol i 1 was purified from venom, proteolytic peptides prepared and amino acid sequences obtained. The cDNA for Sol i 1 was cloned, sequenced, and compared with sequences of other wasp venom phospholipases. The role of carbohydrate epitopes in the cross-reactivity with other Hymenoptera venoms was studied by RAST inhibition. RESULTS: The sequence identified Sol i 1 as a lipase of the GX class, lipoprotein lipase superfamily, pancreatic lipase homologous family and RP2 subgroup phospholipases as are the vespid venom phospholipases. The 148 residues identified by amino acid sequencing represent about 48% of the translated cDNA sequence. Sol i 1 was 31-32% identical to yellow jacket phospholipases. The identical regions of sequence were clustered in the domain which forms the serine hydrolase active site. Mannosylated N-glycans could completely inhibit binding of IgE from honeybee venom sensitized patients to Sol i 1. Inhibition by glycan of IgE binding from yellow jacket venom sensitized patients was low or absent for three of eight sera and substantial, but not complete for five sera. CONCLUSIONS: Sol i 1 is related to wasp venom phospholipases. Cross-reactivity with honeybee venom is caused by carbohydrate, whereas cross-reactivity with yellow jacket venom involves reactivity with both carbohydrate determinants of hyaluronidase and high molecular weight proteins and phospholipase protein determinants.
BACKGROUND: Recent studies have shown the presence of additional allergenic proteins in honeybee and paper wasp venoms. Both venoms contain serine protease enzymes. OBJECTIVE: We isolated and obtained complete sequences of honeybee and Mediterranean paper wasp venom proteases, both of which have significant IgE binding activity. The structures are compared with bumblebee venom protease. METHODS: Venom proteases were chromatographically isolated from venoms and partial amino acid sequences determined. RT-PCR and rapid amplification of cDNA ends methods were used to clone cDNA, and complete sequences were determined for honeybee and a paper wasp venom protease. RESULTS: The venom proteases are all serine proteases of the trypsin type. The honeybee protease contains a complement, embryonic sea urchin protein, bone morphogenetic protein interaction domain as well as a linker and propeptide sequence, and a unique methionine residue near the active site. It has IgE binding activity. The paper wasp protease is a single trypsin domain and is an important allergen. The framework residues are poorly conserved among honeybee, bumblebee, and paper wasp enzymes. CONCLUSIONS: The 3 venom serine proteases have significant IgE binding activities. The structures are poorly conserved even among the Apidae , suggesting little cross-reactivity among the protein portions. The paper wasp venom proteases are important allergens.
BACKGROUND: Mosquito bite-induced acute systemic allergic reactions are an increasing clinical concern and have not been optimally characterized immunologically. OBJECTIVE: We wanted to study the immunologic basis of these reactions. METHODS: Sera were received from 14 individuals with a history of acute systemic allergic reactions to mosquito bites, defined as the presence of one or more of the following: urticaria, angioedema, wheezing, dyspnea, hypotension, and decrease or loss of consciousness. Ten individuals were from the United States and one each was from Canada, Germany, Japan, and Switzerland. An indirect ELISA was developed to measure specific IgE and IgG antibodies to saliva from 5 common mosquito species with different geographic distributions: Aedes aegypti, Aedes vexans, Aedes albopictus, Anopheles sinensis, and Culex quinquefasciatus. Twenty-nine individuals with negative bite test results from laboratory-reared mosquitoes served as control subjects. RESULTS: Mosquito saliva-specific IgE levels to all 5 species were significantly increased in the individuals with systemic allergic reactions compared with the control subjects ( P < .061 for Aedes vexans and P < .008 for the remaining 4 species). By using the mean of the control subjects plus 1 SD as a cut-off level, 11 individuals had positive results to Aedes albopictus and up to 4 additional species; 3 individuals had positive results to only one species. Saliva-specific IgG levels were not significantly increased in the individuals with systemic allergic reactions compared with levels seen in the control subjects ( P > .05). CONCLUSION: Acute systemic allergic reactions to mosquito bites involve mosquito saliva-specific IgE and can be characterized immunologically. Aedes albopictus is the most common species associated with systemic allergic reactions to mosquito bites.
Allergic reactions to vespid stings are one of the major causes of IgE-mediated anaphylaxis. Vespa and Vespula venoms are closely related; Polistes venom is more distantly related and its allergens are less well studied. There is limited cross-reactivity between Polistes and the other vespid venoms because of differences in the epitopes on the allergen molecules. In this study, the major allergens of Polistes gallicus are isolated and characterized. P. gallicus venom contains four major allergens: phospholipase, antigen 5 (Ag5), hyaluronidase and protease that were characterized by mass spectrometry and specific binding to IgE. The complete amino acid sequence of Ag5 and the sequence of the N-terminal region of phospholipase were also determined. The alignment of Ag5 from P. gallicus (European species) and Polistes annularis (American species) shows an 85% identity that increases to 98% within the same subgenus. This could suggest the presence of specific epitopes on Ag5 molecule being the variations on the superficial loops. The features of the P. gallicus allergens could explain the partial cross-reactivity found between the American and European Polistes venoms, and suggest that the use of European Polistes venoms would improve the diagnostic specificity and the therapy of European patients and of North American patients sensitized by European Polistes.
For more than 20 years venom immunotherapy has been the preferred treatment for Hymenoptera allergy and venom skin testing the preferred diagnostic test. Most allergists consider venom skin tests to be highly accurate and interpret a negative venom skin test result to indicate the absence of insect allergy. Furthermore, current practice guidelines do not adequately address the question of how best to manage the patient with a convincing history of insect allergy but negative skin test results. Recent case reports and published studies have forced us to reexamine this important management issue and to consider what role in vitro venom testing might have in the management of insect allergy. We reviewed the current status of what is known about the management of individuals with a history of insect allergy but negative venom skin test results and suggested modifications of current working guidelines.
Previous studies measuring immunoglobulin E (IgE) antibodies in postmortem sera for determining the cause of fatal anaphylaxis have reported only single cases or small groups. Recently, more attention has been paid to reports of patients with venom allergies who are negative by venom skin testing, by in vitro testing or by both tests. The aim of this study was to determine the reliability of postmortem-specific IgE antibody testing in venom anaphylactic death and the range of antibody levels found. Radioallergosorbent testing was performed on sera from three groups: 51 anaphylactic deaths from insect stings, 20 anaphylactic/anaphylactoid deaths from food and drugs, and 31 control subjects. Results were analyzed by descriptive statistics, chi-squared test, and receiver operating characteristic curve. The sera in the sting death group were significantly different from the other two groups, which were not statistically different from each other. The maximal sensitivity of the radioallergosorbent test was 90% at 0.35 ng/mL, and the optimal sensitivity was 73% with a specificity of 86% at 0.54 ng/mL. IgE antibody could not be detected in 10% of the sting death sera and levels from 0.35 to 0.65 ng/mL were found in 24%. The level of specific IgE antibodies against venoms is not predictive of the severity of anaphylactic reaction.