Question

what do you mean by delayed type of hypersensitivity?​

Answer 1

Answer:

Delayed-type hypersensitivity (DTH) is a unique type of cell-mediated immunity. The name originated from the skin test used in the diagnosis of tuberculosis and denotes cellular infiltrates causing induration and erythema at the skin test site within 24 to 72 hours. DTH was coined to describe the reaction to the tuberculosis skin test and to differentiate between delayed cellular skin test results and antibody-mediated immediate skin test results. The term has been expanded to include cell-mediated reactions to bacteria or fungi infecting lungs and skin responses to chemicals and plants. In the lung, cellular responses to tuberculosis, histoplasmosis, and coccidioidomycosis are considered DTH reactions. Skin reactions to nickel and poison ivy also are DTH reactions.

Answer 2

Delayed hypersensitivity is a common immune response that occurs through direct action of sensitized T cells when stimulated by contact with antigen. It is referred to as a delayed response in that it will usually require 12–24 hours at a minimum for signs of inflammation to occur locally.
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