Proteinase and gelatinolytic activities of house dust mite and cockroach extracts.

The presence of gelatinolytic activity in dust mite and Periplaneta americana allergenic crude extracts were studied. The former presented major activity in a broad band between 45 and 66 kDa and minor activity at 32 kDa, while the latter showed a more complex pattern with gelatinolytic activity at 90, 78, 65, 34, 32 and 24 kDa. When the proteolytic activity patterns of dust mites and cockroach crude extracts were analyzed at three different pH levels, the proteases in both cases were optimally active at pH 6, showed no activity at pH 3.5 and little activity at pH 8.5. The susceptibility of both extracts to a set of well-known protease inhibitors suggested that they are composed of cysteine and serine proteinases, the latter probably being a trypsin-like type. When immunochemical properties were studied, dust mite bands of about 200, 110, 65, 60 and 43 kDa showed immunoreactivity against a polyclonal human anti-dust mite serum, with the band of approximately 200 kDa presenting the highest antigenicity. A similar analysis was applied to the cockroach extract, which exhibited immunoreactive bands at 90, 78, 65 and 34 kDa when incubated with a polyclonal rabbit anti-Blatta serum. Only those of 90, 78 and 65 kDa reacted against a polyclonal human anti-Blatta serum. These results suggested a correlation between some proteases with gelatinolytic activity and the allergenicity of both extracts.