DTH reactions may include, but are not limited to, contact dermatitis (eg, poison ivy rash), tuberculin skin test reactions, granulomatous inflammation (eg, sarcoidosis, Crohn disease), allograft rejection, graft versus host disease, and autoimmune hypersensitivity reactions.
tricks of the trade. 1  Clever ways of operating a business or performing a task or activity, especially slightly dishonest or unfair ones. For example, Alma knows all the tricks of the trade, cutting the fabric as close as possible, or The butcher weighs meat after it's wrapped; charging for the packaging is one of the tricks of the trade.
Trade, or commerce, involves the transfer of goods or services from one person or entity to another, often in exchange for money. A network that allows trade is called a market. The original form of trade, barter, saw the direct exchange of goods and services for other goods and services. Barter is trading things without the use of money. Later one side of the barter started to involve precious metals, which gained symbolic as well as practical importance.