| Summary: | Because tumours are comprised of "self" cells and antigens, they escape recognition by the immune system, which discriminates between "self" and "non-self". One such antigen is cathepsin B, a lysosomal cysteine proteinase, that has been implicated as one of the proteolytic enzymes involved in tumour invasion and metastasis. Cathepsin B autoantibodies
could open possibilities which may be useful in cancer immunotherapy. In this study generation of cathepsin B autoantibodies was attempted by manipulating the immune system into recognising and responding to cathepsin B in complex with a "foreign" protein, bovine serum albumin (BSA). Cathepsin B was isolated from rabbit liver using the three phase partitioning (TPP) method, modified by adding t-butanol in the homogenisation buffer. Isolation of cathepsin Band cathepsin L, using this novel method, minimised the formation of artefacts such as a covalent
cathepsin L-stefin B complex and produced higher yields of enzyme.
Pure rabbit liver cathepsin B was conjugated to BSA, using glutaraldehyde as coupling agent, and administered intramuscularly into rabbits. Another three inoculation protocols, which functioned as controls were: i) free cathepsin B administered intramuscularly, ii) complexed cathepsin B administered intravenously, and iii) free cathepsin B administered intravenously. IgGs isolated from inoculated rabbits' serum were assayed by a three layer ELISA system, immunoinhibition assays and dot blots. The anti-complex (intramuscular) antibodies showed the highest recognition for cathepsin B and were the only antibodies that were immunoinhibitory. This suggests that the immune system was, to some extend, successfully
manipulated into recognising the complexed "self" cathepsin B. === Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.
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