BIOCHEMICAL-ANALYSIS AND IMMUNOGENICITY OF LEISHMANIA-MAJOR AMASTIGOTE FRACTIONS IN CUTANEOUS LEISHMANIASIS

Soluble Leishmania antigen (SLA) from both developmental stages of L. major (L. major MRHO/IR/75/ER) were prepared. Three and five subfracti ons of SLA from amastigote and promastigote were obtained by fast prot ein liquid chromatography (FPLC), respectively. Biochemical analyses a nd comparison of amastigote and promastigote SLA were done. The bioche mical analyses revealed that the first fraction of L. major amastigote possesses a distinct band on its electrophoretic mobility pattern cor responding to a position of 24 kD, and it has enzymatic activity with characteristics of a cysteine proteinase. The isolated fractions of am astigote were tested for induction of proliferation, interferon-gamma (IFN-gamma) and IL-4 production in cultures of peripheral blood mononu clear cells (PBMC) from individuals who had recovered and also chronic patients of cutaneous leishmaniasis caused by L. major. The cells of recovered individuals compared with chronic cases proliferated profoun dly in response to the first fraction of amastigote SLA. In all recove red individuals, the IFN-gamma, but not IL-4, was secreted in response to stimulation with the first fraction of amastigote SLA. In chronic cutaneous leishmaniasis, IFN-gamma was infrequently observed in respon se to stimulation by all three fractions of amastigote SLA, but secret ion of IL-4 was observed. These data indicate that first fraction of a mastigote SLA is a strong inducer of primed human immune response to L . major, and may have a protective function.