T Cell Response of Asymptomatic Leishmania chagasi Infected Subjects to Recombinant Leishmania Antigens

Abstract

In areas of Leishmania chagasi transmission the ability to control leishmania infection is associated with IFN-g production. In visceral leishmaniasis down-regulation of T cell responses is mediated by . In this study we evaluated the lymphoproliferative response, IFN-g and IL-

Novas evidências sobre o valor diagnóstico da reação de imunofluorescência indireta e reação intradérmica de hipersensibilidade tardia na infecção humana por Leishmania (L.) infantum chagasi na Amazônia, Brasil

“…29 In a previous study , a similar situation was observed in an AVL-endemic area in the Municipality of Barcarena, Pará, around 150 km from the location of the present study; in that study, the AI profile corresponded to 73.2% of all cases of infection regarding their cumulative prevalence. Therefore, considering that delayed-type hypersensitivity 18 represents a strong expression of cellular immune 33,10 resistance against infection with L. (L.) i. chagasi, these results confirm that the vast majority (final distribution of the AI profile, 78.3%) of infected individuals in an endemic area are genetically resistant to infection. Also, considering that the SRI profile (final distribution, 15.1%) represents an evolutionary stage of infection with respect to the resistant pole (AI profile), the AI frequency could reach 90% in an endemic area.…”

“…Until recently, the clinical spectrum of infection was thought to vary between asymptomatic infection, found in resistant individuals with a strong cellular immune response (consisting of delayed hypersensitivity, lymphocyte proliferation, and the production of gammainterferon), and a symptomatic form found in susceptible individuals in whom suppression of this cellular immune 15,33 response may lead to classical AVL . However, in addition to these extreme forms of infection, individuals may present with an intermediate, "borderline" form known as subclinical oligosymptomatic infection, whose clinical and immunological characteristics are still not entirely 27,10 clear .…”

Elongation Factor-2, a Th1 Stimulatory Protein of Leishmania donovani, Generates Strong IFN-γ and IL-12 Response in Cured Leishmania-Infected Patients/Hamsters and Protects Hamsters against Leishmania Challenge

“…Thus, individuals who control parasite burden successfully either following treatment in the case of patients or due to adequate immunity, as in endemic contacts, exhibit good T cell reactivity to the Leishmania Ag. The presence of a positive immune response in all of the five endemic contacts suggests that the frequency of subclinical infection in an endemic area such as Bihar is high, as has been reported in other areas of the world (38)(39)(40). The majority of people infected with L. chagasi or L. donovani have been shown to clear their infection spontaneously and develop protective immunity, characterized by lymphocyte proliferation and secretion of IFN-g in response to Ag in vitro.…”

Nucleosomal Histone Proteins of L. donovani: A Combination of Recombinant H2A, H2B, H3 and H4 Proteins Were Highly Immunogenic and Offered Optimum Prophylactic Efficacy against Leishmania Challenge in Hamsters

“…The presence of a positive immune response in all the eight endemic contacts indicates towards the high frequency of sub-clinical infection in an endemic area such as Bihar, India as has been reported in other endemic parts of the world [32], [33], [34]. It is well established that recovery from Leishmania infection, relies on induction of the Th1 response [35], [36] particularly the production of IFN-γ and IL-12 and improved expression of iNOS [30], [37].…”