Soluble Leishmanin as an Ideal Reagent for Skin Testing in Human Leishmaniasis

Delayed-type hypersensitivity reaction measured by skin testing, is an important tool for evaluation of cellular immune response in leishmaniasis and has been used recently as an indication of exposure to infection. Skin testing in leishmania infection needs a standard reagent with high specificity, sensitivity, and potency. In the present work, a soluble leishmanin, and three whole parasite preparations from Leishmania major, i.e. thimerosal, phenol, and autoclaved leishmanins, were prepared under standard conditions. These antigens were evaluated and compared in different foci of leishmaniasis. The sensitivity and potency of reagents were tested in both recovered cases and patients with active ulcer in two areas endemic to urban and rural leishmaniasis. Data obtained showed that, the sensitivity of thimerosal, phenol, and soluble leishmanins are almost equal, but are higher than autoclaved one. Moreover, the potency of soluble leishmanin was also proved to be higher than other reagents. The purity of soluble leishmanin is higher than other three particulate preparations, and it lacks the majority of membrane antigens. As a result this reagent can be used as a standard and ideal antigen for skin testing in human leishmaniasis