AJP - Regulatory, Integrative and Comparative Physiology, Vol 260, Issue 2 314-R320, Copyright © 1991 by American Physiological Society
Cysteine proteinase inhibitor in eccrine sweat is derived from sweat gland
H. Yokozeki, T. Hibino, T. Takemura and K. Sato
Marshall Dermatology Research Laboratories, Department of Dermatology, University of Iowa College of Medicine, Iowa City 52242.
Although cysteine proteinases have been reported to be present in human
eccrine sweat, their endogenous inhibitors, cysteine proteinase inhibitors
(CPIs), have remained unstudied. We now present evidence that CPIs are
indeed a true ingredient of human eccrine sweat. Sweat induced in sauna was
collected over a Vaseline barrier placed on the skin to minimize epidermal
contamination. The absence of major epidermal contamination of the sweat
was further ensured by monitoring an epidermal marker, high-molecular-mass
aminopeptidase. Sweat CPI was purified sequentially by chromatography with
Sephacryl S-200, carboxymethylated papain-Sepharose, and anion-exchange
Mono Q fast-protein liquid chromatography columns. Sweat CPI has a
molecular mass of approximately 15 kDa, is stable for temperature (up to 80
degrees C) and pH (from 3 to 10), and inhibits papain, ficin, and sweat
cathepsin B- and H-like enzymes. Sweat CPI may be of sweat gland origin
because 1) the rate of CPI output in sweat (CPI concentration x sweat rate)
is constant over 45 min; 2) antibody against epidermal CPI, which
cross-reacts with sweat CPI, localized immunoreactivity in the sweat duct;
3) CPI activity was present in the glandular extracts of control and
methacholine-stimulated (for 1 h in vitro) human sweat glands; and 4) the
peaks of CPI activity in the glandular extract and sweat CPI were both
eluted (by high-pressure liquid chromatography) at around 15 kDa. Sweat CPI
may be very similar to epidermal CPI (which belongs to the stefin family of
CPIs) because of many shared characteristics. The identity and function of
sweat CPI remain to be studied.
