Peripheral blood leucocytes subpopulation dynamics during Trypanosoma congolense infection in Boran and N'Dama cattle: an analysis using monoclonal antibodies and flow cytometry

Abstract

A panel of monoclonal antibodies (MoAb) with specificities for bovine leucocyte subsets were used in conjunction with routine haematological procedures to analyse sequential changes in peripheral blood leucocyte populations during the course of tsetse fly-transmitted Trypanosoma congolense infection in trypanotolerant N'Dama and trypanosusceptible Boran cattle. Subsequent to the first parasitaemic wave, the N'Dama cattle maintained packed cell volumes (PCV) above 22 and lower levels of parasitaemia than Boran throughout the 160 days of the experiment. In contrast, the Borans developed severe anaemia and required curative drug therapy (i.e., PCV dropped to less than 15) by 55 days (range: 22-55 days) post infection. There were significant (P less than 0.05) decreases in total white blood cells and total lymphocytes from pre-infection levels to the first peak of parasitaemia (day 16 post-infection) in both groups. Flow cytometric analyses using MoABs revealed that this change was due to an absolute decrease in T cells expressing BoT2 and either BoT4 or BoT8, surface immunoglobulin M-positive (sIgM+) B cells, and null cells which did not express T cell, B cell or monocyte markers. During this period there was significant variation over time, but no overall increase or decrease, in the number of cells expressing class II major histocompatibility (MHC) molecules or monocyte markers, or in the number of circulating neutrophils or eosinophils. The BoT4/BoT8 ratios were significantly (P less than 0.01) increased in both groups of infected animals at the first peak of parasitaemia. After day 22 in the infected N'Damas and in the Borans which required drug therapy, there was a leucocytotic response characterized by an increase in the total number of B cells, T cells, and null cells. Prior to infection and throughout the course of the experiment N'Dama cattle had significantly (P less than 0.01) higher numbers of B cells and null cells than Boran.

Haematological changes in sheep experimentally infected with Trypanosoma evansi

“…This observation is in agreement with studies in cattle and sheep experimentally infected with T. congolense (Fiennes et al 1946;Naylor 1971;Wellde et al 1974;Valli and Mills 1980;Ellis et al 1987;Mwangi 1991;Williams et al 1991). The leucocytosis was a result of marked lymphocytosis since both the proportions and numbers of neutrophils and eosinophils decreased irrespective of the increased TWBC counts.…”

Changes in peripheral blood lymphocyte subpopulations and parasite-specific antibody responses in Trypanosoma evansi infection of sheep

“…In the former group the moderate increase was clearly biphasic and the second phase along with the second phases of the increases in the numbers of CD5 + and CD4 + T-cells coincided with the period of parasite control and self-cure. Thus, although the presence of high levels of circulating B-cells has been suggested as a possible reason for the ability of trypanotolerant N'dama cattle to control T. congolense infection (Ellis et al 1987), results of this study indicate otherwise, since animals in which the numbers of B-cells more than doubled during the infection failed to eliminate the parasites. It would therefore appear that the resistance that develops may depend not simply on massive increases in B-cell numbers but, more importantly, on the rate and pattern of B-cell proliferation and the numbers and ratio of CD4 and CD8 expression.…”

“…This failure is, in part, due to the generalised immunosuppression that is characteristic of trypanosomosis in rodents (Goodwin et al 1972) and in domesticated livestock Sileghem 1991, 1993;Sileghem and Flynn 1992;Onah et al 1998a). Alterations in the dynamics of expression of speci®c lymphocyte subsets probably underlie the immune dysfunction seen in human trypanosomosis, Chagas' disease caused by Trypanosoma cruzi (Beltz et al 1988), and in bovine and ovine trypanosomosis caused by T. congolense (Ellis et al 1987;Mwangi 1991;Williams et al 1991). This immunosuppression is also temporarily related to alterations in the lymphocyte composition of the chancre in the skin at the site of infective¯y bite, in the draining lymph node and associated lymphatics and in the peripheral blood (Mwangi 1991;Mwangi et al 1990Mwangi et al , 1991Mwangi et al , 1996.…”

The potential impact of native Australian trypanosome infections on the health of koalas (Phascolarctos cinereus)

“…A significant regenerative anaemia was observed in a small number of koalas that were infected with a trypanosome as evidenced by the presence of abnormally increased numbers of reticulocytes and nucleated erythrocytes (normoblasts) supported by hypercellular bone marrow on prepared blood and bone marrow smears (A. Gillett, personal communication). Anaemia is commonly associated with human (Chisi et al 2004) and animal trypanosomiasis, reported in native African cattle breeds (Ellis et al 1987;Sekoni et al 1990;Akinbamijo et al 1998;Mahama et al 2004), horses (Silva et al 1995), pigs (Omeke and Ugwu, 1991), sheep (Katunguka-Rwakishaya et al 1992;Onah et al 1996), goats (Goossens et al 1998;Ogunsanmi and Taiwo, 2001;Faye et al 2005) and dogs (Onyeyili and Anika, 1990;Egbe-Nwiyi and Antia, 1993) and cats (Da Silva et al 2009). Anaemia is, however, not always noted with trypanosome infections, in part due to the fact that numerous trypanosomes are non-pathogenic and also due to the variable disease dynamics of pathogenic trypanosomes.…”