Several hypotheses have been put forth as to the mechanisms by which proteolytic enzymes modulate the immune system to control and eliminate tumors. Some studies indicated that proteolytic enzymes selectively remove some adhesion molecules such as CD4, CD44, B7-1, ICAM-1, B7-2, CD45RA, CD6, CD7, E2/MIC2, and Leu81/LAM 1 from cell surfaces According to Hale et al. the removal of these surface molecules has markedly enhanced CD2 mediated T-cell activity.
Some studies have implied that by removing the glycoprotein CD44, some proteases help control the tumor growth of certain types of cells. This selective removal of some mediator proteins, and the regulation of cytokines constitute some factors by which proteolytic enzymes are thought to modulate the immune system and act as biological response modifiers.