Trypanosoma congolense infection in sheep: cellular phenotypes in lymph and lymph nodes associated with skin reactions.

Intradermal inoculation of sheep with culture-derived metacyclic forms of Trypanosoma congolense resulted in the development of localized skin reactions (chancres) and enlargement of the draining lymph nodes 7 days after infection. Changes in the expression of surface antigens of lymphocytes in lymph leaving the affected skin reactions and in the associated lymph nodes were monitored by cannulating the afferent and efferent lymphatic ducts. Trypanosomes appeared in afferent and efferent lymph 3 to 5 days after infection and persisted even as the chancres regressed. The cellular output in both afferent and efferent lymph increased markedly after the onset of parasitosis. Sequential analysis of the phenotypes of lymphocytes by immunofluorescent staining and flow cytometry revealed that in afferent lymph draining the chancre there was an early response which was due to an increase in T cells, particularly CD4+ and CD8+ cells; however, as the chancres-regressed there was an increase in lymphoblasts and surface immunoglobulin-bearing cells. In contrast, in the efferent lymph, the increase in lymphocytes was due predominantly to a higher number of cells bearing surface immunoglobulins.

The sequential cellular changes in the local skin reaction produced in goats by Glossina morsitans morsitans infected with Trypanosoma (Trypanozoon) brucei.

Sequential biopsies of the skin reaction elicited in goats by Glossina morsitans morsitans infected with Trypanosoma (Trypanozoon) brucei were examined histologically to identify and to quantify the cellular populations involved in the reaction. The peak of the tissue response occurred 7-8 days after challenge with infected tsetse and preceded the initial detection of parasitaemia by 4-5 days. Microscopically, the cellular reaction was characterized initially by a marked infiltration of polymorphonuclear leucocytes (PMN) which were replaced by lymphoid cells. Plasma cells and macrophages were numerous during the decline of the skin reaction. Marked enlargement of, and germinal centre formation in the regional lymph node accompanied the development and regression of the chancre. The results suggest that the formation of a chancre is dependent on the skin thickness of the host at the site of tsetse challenge.