Skin testing with stsndard leishmanin of Iran

ABSTRACT

Delayed-type hypersensitivity [DTH] reaction measured by skin testing is an important indicator for evaluation of cellular immune response in leishmaniasis. Skin testing in leishmaniasis, known as leishmanin or Montenegro test, is used normally for immunoepidemiological studies and for diagnosis. In cutaneous leishmaniasis [CL], the skin test is positive during the active phase of disease and remains reactive in almost 100% of recovered cases. The present paper describes the preparation and evaluation of the standard leishmanins produced from a well characterized strain of Leishmania major, and their applications in human CL, Different batches of leishmanin preparations were prepared in standard conditions and their reactivities were tested in different areas. Specificity of reagents was evaluated in healthy individuals in non endemic area of Tehran. Sensitivity and potency of antigens were evaluated in recovered cases from cutaneous leishmaniasis [CL] in endemic areas for both urban CL [north - west of Tehran] and rural CL [Isfahan area].The skin testing was carried out by intradermally injection of 0.1 ml of antigen or control regent into forearm of the individuals. Data obtained showed that specificity is 100% for all preparations. In recovered cases, different batches of leishmanin showed high sensitivity in different foci of leishmaniasis [> 93% in urban CL foci, and > 95.83% in rural CL foci]. Also different batches of leishmanin demonstrated a reliable potency in cured cases from urban CL, with mean diameter of indurations between 11.85 +/- 3.78mmand 14.21 + 5.0 mm. Moreover, strong potency was found in healed cases of rural CL with mean indurations between 15.18+ 3.93 mm and 18.04 + 5.22 mm. Finally, the reactivity of leishmanin was tested and proved stable after eight years study in recovered cases, This standard leishmanin, has also been tested in research centers of the country and abroad, and compared with other reagents, and selected by FDR as a reference reagent for vaccine trials