Proteinase and gelatinolytic properties of a Triatoma infestans extract.

An extract of Triatoma infestans has previously been demonstrated to produce specific IgG and IgE both in animals and in atopic humans with rhinitis/asthma as well as hypersensitivity pneumonitis in guinea pigs aerosolized with T. infestans. We attempted to determine whether the antigen or antigens responsible belonged to the protease group, as occurs with other allergens such as house dust mites and cockroaches. To do this, T. infestans was studied by SDS-PAGE, Western blots and gelatinolysis with and without the use of specific protease inhibitors such as E-64, TLCK, TPCK, PMSF, leupeptin, o-phenanthrolene and pepstatin-A. These assays revealed serine-like proteolytic and gelatinolytic activities. The presence of 10 to 12 bands of between 14 and 100 kDa was detected. The proteolytic activity pattern of T. infestans was greatest at pH 8.5 and gelatinolytic activity was highly sensitive to PMSF, suggesting that this enzyme could be characterized as a serine protease. Western blots revealed that two bands of 17 and 58 kDA reacted with the sera of atopic humans with respiratory diseases and anti-IgE. However, whether these bands correlated with allergenicity is unclear since the presence of several proteins in each of these bands does not rule out the possibility that this correlation could exist, especially because cross-reactions with antigens from the cockroach Periplaneta americana and its specific antiserum in animals and atopic humans have been demonstrated. The role of proteases in the etiopathogenesis of perennial rhinitis and bronchial asthma in inhabitants of the area of Argentina infested by T. infestans requires further investigation.