Vásquez JE, Krusnell J, Ö rn A, Sousa OE, Harris RA. Serological Diagnosis of Trypanosoma rangeli Infected Patients. A Comparison of Different Methods and its Implications for the Diagnosis of Chagas' Disease. Scand J Immunol 1997;45:322-330 Venous blood from 65 Panamanian schoolchildren living in an area endemic for both Trypanosoma cruzi and T. rangeli were screened for the presence of these parasites. Trypanosoma rangeli were isolated and cultured from four individuals. Serological tests of all 65 sera were performed, including immunohaemagglutination (IHA), indirect immunofluorescence assay (IF) and ELISA using both T. rangeli and T. cruzi as antigens, as well as T. cruzi synthetic peptides in an ELISA assay. Results indicated a higher immunoreactivity to T. rangeli preparations than to T. cruzi within the studied population, which could be divided into four 'serological responder' groups. Interestingly, the panel of SAPA and other T. cruzi synthetic peptides were not useful in the discrimination of patients. Furthermore, patients from whom parasites had been isolated could not be distinguished from those of two other groups. Significant immunoreactivity to T. cruzi preparations was displayed in all responder sera, despite total lack of evidence of infection with this parasite. The immunobiological significance of T. rangeli infection is unclear, but these data indicate that it is a compounding problem in the accurate diagnosis of pathological T. cruzi infection by serological analysis. The relationship of these cohabiting species, in respect to infection outcome and immunological activation, is discussed.

Guevara-Mendoza O, Une C, Franceschi Carreira P, Ö rn A. Experimental Infection of Balb/c Mice with Leishmania panamensis and Leishmania mexicana: Induction of Early IFN-g but not IL-4 is Associated with the Development of Cutaneous Lesions. Scand J Immunol 1997;46:35-40 Resistance to the Leishmaniae is associated with interferon (IFN)-g mediated activation of macrophages. In this study, Balb/c mice were infected with three Leishmania strains that cause progressively growing cutaneous lesions without obvious dissemination; L. mexicana mexicana giving rise to rapidly growing lesions, and L. (Viannia) panamensis and L. mexicana-like, which both cause slowly developing lesions. The rate of lesion growth was compared to induction of early local and systemic IFN-g responses. All the three parasite strains induced increased levels of IFN-g transcripts 24 h after infection. Infection with the more aggressive strain resulted in a notably lower IFN-g response when compared to infection with the two low pathogenic strains. Interleukin-4 (IL-4) mRNA appeared 7 days after infection with L. (Viannia) panamensis and L. mexicana-like but not with L. mexicana mexicana. Thus, virulence of these Leishmania strains could not be associated with induction of IL-4 during the first week after infection. In addition, none of the Leishmania strains induced detectable mRNA for IL-12 or inducible nitric oxide synthase (iNOS). These data present a picture somewhat different from that which has been described in L. major experimental infection.

No abstract

No abstract

We studied the susceptibility to Leishmania (Viannia) panamensis in strains of mice. The C57BL/6 strain was resistant and showed self-controlled lesion at the injected foot pad. The BALB/c and DBA/2J strains were susceptible and showed a foot swelling that started day 20 post-infection and progressed to a tumour-like lesion in later period of observation. The CBA/HJ strain was found to be of intermediary resistance. In contrast to other known cutaneous leishmaniasis in mice, the lesion in L. (V.) panamensis-infected mice was restricted to the inoculation site in the skin. In addition, we studied the development of cellular response and antibodies against Leishmania antigen in BALB/c and C57BL/6 strains. The proliferative response of lymph node cells against L. (V.) panamensis antigen was biphasic in both strains. An initial response was seen on day 20, followed by a refractory period between 40 and 80 days and a second response around fourth month post-infection. The response in the latter period was higher in C57BL/6 strain than in BALB/c strain. BALB/c strain presented much higher anti-Leishmania antibody level than C57BL/6 strain. The model and the correlation of immunological variables and the course of the infection are discussed.