1. Myelopeptide-1 blocks the T-suppressor activity
R V Petrov, A A Mikhailova, E A Kirilina Folia Biol (Praha). 1994;40(6):455-61.
The immunoregulatory properties of two myelopeptides (MPs) [Phe-Leu-Gly-Phe-Pro-Thr (MP-1) and Leu-Val-Val-Tyr-Pro-Trp (MP-2)] were studied. The antibody production-stimulating activity was determined in the culture of lymph node cells (LNC) obtained from mice on the 4th day of the secondary immune response to sheep red blood cells (SRBC). T suppressors were induced in mouse spleen cell (SC) culture by incubation with concanavalin A (Con A) for 48 h. Immune LNC were cultured alone or with T suppressors in the presence or absence of MPs. After cultivation, the immune response was estimated by enumeration of indirect antibody forming cells (AFC). MP-1, but not MP-2, increased the number of AFC and abolished Con A induction of T suppressors in SC suspensions. MP-1 also fully blocked and MP-2 only partly decreased the inhibitory effect of T suppressors in the culture of immune LNC. Immunoregulatory peptide MP-1 may participate in regulation of the antibody response and in development of some states of immunological tolerance.
2. Development and validation of a simple cell-based fluorescence assay for dipeptidyl peptidase 1 (DPP1) activity
Bob Thong, James Pilling, Edward Ainscow, Raj Beri, John Unitt J Biomol Screen. 2011 Jan;16(1):36-43. doi: 10.1177/1087057110385228. Epub 2010 Nov 18.
Dipeptidyl peptidase 1 (DPP1) (EC 3.4.14.1; also known as cathepsin C, cathepsin J, dipeptidyl aminopeptidase, and dipeptidyl aminotransferase) is a lysosomal cysteinyl protease of the papain family involved in the intracellular degradation of proteins. Isolated enzyme assays for DPP1 activity using a variety of synthetic substrates such as dipeptide or peptide linked to amino-methyl-coumarin (AMC) or other fluorophores are well established. There is, however, no report of a simple whole-cell-based assay for measuring lysosomal DPP1 activity other than the use of flow cytometry (fluorescence-activated cell sorting) or the use of invasive activity-based probes or the production of physiological products such as neutrophil elastase. The authors investigated a number of DPP1 fluorogenic substrates that have the potential to access the lysosome and enable the measurement of DPP1 enzyme activity in situ. They describe the development and evaluation of a simple noninvasive fluorescence assay for measuring DPP1 activity in fresh or cryopreserved human THP-1 cells using the substrate H-Gly-Phe-AFC (amino-fluoro-coumarin). This cell-based fluorescence assay can be performed in a 96-well plate format and is ideally suited for determining the cell potency of potential DPP1 enzyme inhibitors.
