Kinetics of Trypanosoma cruzi infection in guinea-pigs, with special reference to the involvement of epidermal Langerhans' cells in the induction of immunity

Several studies have confirmed that epidermal Langerhans' cells (LC) play a central role in the induction of skin-related immunological events. In ord er to assess the role of LC in Chagas' disease, guinea-pigs were infected i ntradermally with Trpanosoma cruzi, sacrificed at different time-points, an d their tissues were processed for routine histology, electron microscopy k ind immunohistochemistry. Parasitaemia was observed earliest at day 6 p.i. with 2 peaks at days 9 and 28, and disappeared on day 56 p.i. Parasite-spec ific serum IgG and IgM were first detected on day 12 p.i. The level of IgG gradually increased by day 84 p.i. All the infected guinea-pigs showed sign ificant alterations in the distribution and morphology of epidermal LC duri ng parasitaemia. The number of LC had significantly decreased in the epider mis by day. 3 p.i., only returning to normal levels by day 56 p.i., althoug h the number of LC in the underlying dermis increased concomitantly. Parasi tes were carried to the regional lymph node, where clustering of parasite-l aden dendritic cells (DC) with lymphocytes was seen by electron microscopy. This evidence suggests that LC might be involved in antigen presentation i n Chagas' disease.