Immune responses of Iranian patients with visceral leishmaniasis and recovered individuals to LCR1 of Leishmania infantum.

Visceral leishmaniasis is a serious public health problem. Leishmania infantum is one of its causative agents. LCR1 is an immunogen from L. infantum. Antibodies against this protein have been detected in visceral leishmaniasis patients. The aim of this study was to define the antibody and cellular immune responses against LCR1 in Iranian visceral leishmaniasis patients and recovered individuals. The LCR1 protein was produced in recombinant form. Antibody responses against this protein were studied in Iranian individuals with a recent history of visceral leishmaniasis. Responses of peripheral blood mononuclear cells to this protein were studied in Iranian individuals who had recovered from visceral leishmaniasis. Our data show that (i) there was an antibody response to LCR1 in each individual with a recent history of visceral leishmaniasis studied, (ii) there was neither a proliferative response nor production of gamma interferon (IFN-γ) or interleukin 10 in response to LCR1 by mononuclear cells from individuals who had recovered from visceral leishmaniasis, and (iii) individuals who have recovered from visceral leishmaniasis show ongoing immune responses long after recovery from the disease. These data show that there are no detectable cellular memory responses to LCR1 in Iranian individuals who have recovered from visceral leishmaniasis, while there are detectable antibody responses in patients with this disease. Our data suggest that LCR1 has potential applications for the diagnosis of leishmaniasis through antibody detection, while the application of LCR1 alone for induction of IFN-γ in individuals who recovered from this disease is not supported. The presence of long-lasting immune reactivities in individuals who recovered from the disease may show the necessity of extended medical surveillance for these individuals.