No abstract

The expression of lymphokine genes during infection of virulent (Tulahuén) or mild (CA-I) strains of T. cruzi was studied in mice lacking CD4 and/or CD8 molecules. The increased susceptibility of CD4- and CD4-CD8- mice to infection with CA-I or Tulahuén was parallelled by diminished IFN-gamma mRNA levels. Nitric oxide release and inducible nitric oxide synthase mRNA accumulation by cells from Tulahuén infected CD4- mice was also diminished. CD8- (but not CD4-CD8- mice) showed an increased IL-4 and IL-10 mRNA accumulation upon infection with both strains of T. cruzi. A 'Th2-like' response (higher IL-4 and IL-10 mRNA to IFN-gamma mRNA ratio), was also observed when cells from noninfected CD8- mice were stimulated with T cell mitogens.

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.