Immunobiology of the serine protease allergens from house dust mites.

Extracts of Dermatophagoides pteronyssinus and D. farinae were shown to contain a variety of 30 kDa serine proteases, including trypsin, chymotrypsin, and an elastase-like enzyme. The mite trypsin, unlike chymotrypsin and the elastase enzyme, was heterogeneous with regard to charge. The enzymes were shown to be present at higher concentration in fecally enriched extracts than in whole mite extracts. The proteases were shown to induce vascular permeability and to detach cells in tissue culture. Further study showed that the mite elastase induced non-IgE mediated rat mast cell degranulation. Such properties may contribute to immunogenicity.

A comparative study of allergenic and potentially allergenic enzymes from Dermatophagoides pteronyssinus, D. farinae and Euroglyphus maynei.

The presence of the enzymatically active allergens equivalent to Der p I (cysteine protease), Der p III (serine protease) and amylase in extracts of Dermatophagoides pteronyssinus, D. farinae and Euroglyphus maynei was determined using appropriate enzymatic techniques. Biochemical equivalents of all three allergens were present in each extract studied. Studies also showed that the mite extracts contained a variety of other biochemically active enzymes including trypsin, chymotrypsin, carboxypeptidase A and B, glucoamylase and lysozyme. Marked differences in the relative concentrations of some of these enzymes in different mite extracts were observed, particularly trypsin and carboxypeptidase A. The enzymes were physicochemically similar to equivalent enzymes from vertebrate and invertebrate sources. Chromatofocusing studies of faecal extracts derived from D. pteronyssinus and D. farinae showed that several isoforms of each enzyme were present. The data indicated that there were more trypsin isoforms, with pI over a wider range, in extracts prepared from D. pteronyssinus. Proteases and carbohydrases were also found in extracts prepared from faecally enriched material suggesting that they were endoperitrophic and associated with mite digestion. The data suggest that not only are the group I, III and amylase allergens a consistent feature of most pyroglyphid dust mites but also that other proteases and carbohydrases present in mite faeces are allergenic.

In vitro synthesis of IgE by human peripheral blood leucocytes: VI. Seasonal variations in synthesis of rye pollen (Lolium perenne) specific IgE.

Fractionation by Percoll density centrifugation of peripheral blood leucocyte cells, from atopic subjects with seasonal hay fever, unmasked IgE-B cell populations whose individual capacities to synthesize IgE in vitro were obscured in cultures of unfractionated B cells. B cell cultures from all six subjects in the study released rye pollen-specific IgE during the 6 days of culture, but actual synthesis was significant only in October, the pollen season. Synthesis in October occurred most frequently in cultures of mature, low density B cells, which generally responded to the addition of autologous T cells with enhanced synthesis (T-help). T-help was also found for high density B cells in the mid-winter (July) cultures. Total IgE synthesis in vitro demonstrated a less seasonal relationship, although it tended to be maximal for low density B cell cultures in October and for high density B cells in May. All B cell cultures contained preformed total and rye-specific IgE antibody which persisted throughout the pre- and post-pollen seasons, particularly in the low density B cell fractions, even in the absence of de novo synthesis. Moreover, the intracellular levels of rye pollen-specific IgE antibody were often higher in the winter than in the peak of the pollen season. The relevance of this preformed IgE remains to be established.