Lepromin Test: Leposy

Table of Contents

The lepromin skin test is used to determine what type of leprosy a person has.
It is a prognostic test that is very helpful in classifying leprosy.
It is similar to tuberculin test
It cannot be used for diagnostic purpose since it is positive in a significant number of normal people and is negative towards the lepromatous pole of the disease.
It is based on delayed type of hypersensitivity (DTH)
Kensuke Mitsuda published the first paper leading to the lepromin reaction (1919). It involves the injection of a standardized extract of the inactivated “leprosy bacillus”,(Mycobacterium leprae or “Hansen’s Bacillus”) under the skin.
Two types of antigens are available:
- Mitsuda lepromin, an autoclaved suspension of tissue (whole bacilli) obtained from experimentally infected armadillos (Lepromin A);
- Dharmendra lepromin, a purified chloroform-ether extracted suspension of M. leprae (fractionated bacilli with soluble protein component).
In India, lepromin antigen is prepared by the Central Leprosy Teaching and Research Institute, Chengalpattu, Tamil Nadu.

Lepromin Test Procedure

An extract sample o.1 mL of inactivated Hansen’s Bacillus/ lepromin(antigen) is intradermally injected just under the skin, usually on the forearm. The injection site is labeled and examined 3 days and 28 days later to see if there is a reaction.

The introduction of lepromin injection gives two types of reactions (diphasic responses).

Early reaction of Fernandez– erythema develops in 24-48 hours and remains for 3-5 days.
Late reaction of Mitsuda– nodule appears after 1-2 weeks.

Applications of lepromin test

Classificationof leprosy patients
- lepromin test is positive for tuberculoid type of leprosy
- Negative in lepromatous type
Assessment the prognosis:
- A positive reaction indicates good prognosis and a negative a bad prognosis. negative to positive indicate good treatment.
Assessment resistance of individuals to leprosy
- Positive lepromin test indicates resistance to Leprosy disease.