Authors: (Hossein Yousofi Darani, Department of Parasitology & Mycology, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran)
Abstract: In different investigations serine proteases have been suggested as possible targets for vaccination. These proteases have also been used in serodiagnosis studies. It has been shown that these enzymes are able to degrade antibodies. Inhibition of proteolitic activity of serine protease by specific antibodies have also been demonstrated. However there is relatively little information about the immunity of these molecules. When serine proteases implicated in immune response process, some of them are considered as poor immunogens and antibody response to them are not detectable using appropriate tests. Furthermore when inbred mice immunized by some serine proteases such as Schistosoma mansoni cercarial protease or porcine pancreatic trypsin, only a minority of them had antibody to the enzymes detectable by western immunoblotting.
Several hypothesis has been postulated to explain why some serine protease are less immunogenic than others. The most likely conception to explain the lack of immuno-genicity of some serine proteases is related to the mechanism that they are processed in antigen presenting cells (APC). It has been shown that in APC, protolytic enzymes are implicated in the generation of peptides which can be loaded into MHC molecules from polypeptide precursors. When the antigen itself is a protease, it may not be processed as a normal antigen.