Cellular and humoral immune responses to vaccmes of hepatitis B type and rabies were Inhibited by specific Inhibitors of cathepsin B. specific synthetic substrates of cathepsin B and anti-cathepsm B antibody. Therefore the lysosomal cathepsin B of antigen presentmg cells plays an essential role in processing of these antigens for presentation to MHC class II. One of the active sites of cathepsin B. VN2,, 122 shares highly homologous sequences with a part of the desetope. a binding domam of antigemc peptides, VN,: h2 of MHC class II, /3-cham. This evidence suggests that the peptides processed by the substrate speclficlty of cathepsm B exhibit a common affinity to bind with the desetope of MHC class II, P-cham.
The primary structure of p31 of invariant chain (Ii-chain) shows about 50% homology with those of the cystatin family which are endogenous cysteine protease inhibitors. The binding domains between Ii-chain and HLA-DR-7 were estimated from the structural homology between cystatin and Ii-chain and also between cathepsins and DR-7, respectively. The QL%,, and GS7c_8, of Ii-chain were estimated to be the binding domains with GGd>j, and VS57-63 of HLA-DR7, respectively. The purified human Ii-chain from spleen is capable of forming four molecular forms from monomer to tetramer by redox-potential dependent disulfide bond formation. The Ii-chain inhibits cathepsin L and H competitively as a dimer and the K, value for cathepsin L was 4.1 x IO-* M, but cathepsin B was not inhibited at all. The Ii-chain showed mainly a dimer (60 kDa) under the assay condition of cathepsins with cysteine and was not degraded by these cathepsins. The Ii-chain may play an important role in the regulation of antigenic peptide presentation to MHC class II.
Hepatocellular carcinoma (HCC) patients can be divided into two groups according to the degree of lymphokine activated killer (LAK) cell activity; a high LAK activity group (H-LAK-HCC) and a low LAK activity group (L-LAK-HCC). Interferon-gamma (IFN-gamma) production is severely defective in L-LAK-HCC but not defective in H-LAH-HCC. IFN-gamma production is suppressed with the addition of anti-Tac in dose dependent manner, though LAK activity is suppressed only in the presence of high concentration of anti-Tac. LAK activity is suppressed with the addition of anti-IFN-gamma, which is most prominent when the antibody is present during the first 12 hr of incubation. LAK generation is enhanced with the addition of recombinant IFN-gamma, which is most prominent when it is present during the first 12 hr of incubation. However, this enhancing effect is less prominent in L-LAK-HCC as compared to normals, liver cirrhosis, and H-LAK-HCC. This enhancement is regarded to depend on the presence of Leu7+ and Leu11+ subset, as this enhancement is abandoned and IFN-gamma production is inhibited when either of these subsets is deleted. These data suggest that IFN-gamma production and the participation of Leu7+ and Leu11+ subsets is important in sufficient LAK generation, and that poor IFN-gamma production and insufficient response to IFN-gamma may be the cause of severely defective LAK generation in L-LAK-HCC.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.