Differential expression of surface membrane antigens on bovine monocytes activated with recombinant cytokines and during Trypanosoma congolense infection

The expression of surface membrane antigens on peripheral blood monocytes (PBM) of cattle of the Boran and N'Dama breeds activated with recombinant cytokines (TNF-α and IFN-γ) and during experimental infection with Trypanosoma congolense was investigated using monoclonal antibodies (MoAbs) and fluorescein-activated cell sorter (FACS). The surface antigens investigated were C3bi receptor, major histocompartibility (MHC) II complex (Ia antigen) and two monocyte/macrophage (MΦ) differentiation antigens. The study revealed that both cytokines caused the enhancement of the expression of all the PBM surface antigens studied. rBoIFN-γ at low concentrations was more efficient in causing the activation of PBM. While the PBM of Boran cattle were more significantly activated to express the C3bi receptor vis-a-vis the Ia antigen than N'Dama cattle, the reverse was the case with the PBM of N'Dama cattle which expressed more Ia antigens than Boran PBM. Similar results were observed during T. congolense infection in the two breeds of cattle. The significantly higher expression of C3bi receptor and correspondingly lower Ia antigen expression by the PBM of Boran cattle, both during trypanosomosis and in vitro may be responsible for the higher rate of erythrocyte phagocytosis, hence the development of more severe anaemia by Boran cattle during trypanosomosis than N'Dama. In addition, the expression of significantly higher numbers of Ia antigen by N'Dama MΦ, hence are more able to process, present and initiate better trypanosome antigen-specific immune response than Boran cattle during infection. These two attributes are known genetic characteristics of trypanotolerance in cattle.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.International Livestock Research Institute (ILRI).mn201

In vitro erythrophagocytosis by cultured macrophages stimulated with extraneous substances and those isolated from the blood, spleen and bone marrow of Boran and N'Dama cattle infected with Trypanosoma congolense and Trypanosoma vivax

A standard radioactive chromium (51 Cr) release assay was used to assess the in vitro phagocytosis and lysis of bovine erythrocytes by cultured splenic, bone marrow and peripheral blood monocytederived (PBM) macrophages isolated from healthy and Trypanosoma congolense and T. vivax-infected cattle of the Boran and N'Dama breeds. Recombinant cytokines (rHuTNF-a and rBoIFN-y) and non-acid-dialysed peripheral blood mononuclear cell (PBMNC) culture supernatants stimulated these PBM for enhanced activities. The stimulants caused increases in the rate of erythrocyte phagocytosis and lysis by cultured PBM in a concentration- dependent manner. But very high stimulant concentrations caused deceased in vitro erythrophagocytosis. However, bacterial lipopolysaccharide (LPS) and acid-dialysed PBMNC culture supernatants did not cause any increase in cultured PBM erythrophagocytosis. In vitro erythrocyte phagocytosis and lysis by splenic, bone marrow and peripheral blood monocyte (PBM)-derived macrophages of Boran breed of cattle infected with Trypanosoma congolense increased from 14 days post-infection (DPI) onwards and thereafter maintained at various levels above pre-infection. Cultured splenic macrophages showed the greatest erythrocyte destruction capability while PBM-derived macrophages was the least. The rates of in vitro erythrocyte phagocytosis and lysis were higher with the cultured PBM of the Beran than those of the N'Dama cattle during T. congolense infection . The rate of in vitro erythrocyte destruction was however, similar in both groups of cattle during T. vivax infection. These results correlated positively with the dynamics and degree of anaemia developed by these groups of animals during both T. congolense and T. vivax infections. Cattle infected with T. congolense and T. vivaxdeveloped varying degrees of normocytic normochromic anaemia during infection. Boran cattle developed a more severe anaemia, and had to be treated with diminazine aceturate, than N'Dama cattle during T. congolense infection. Both breeds of cattle developed a milder but similar degree of anaemia during T. vivax infection. None of the animals were treated. The results of this study indicated a role of in vivo macrophage stimulatory factors, notably cytokines such as TNF-a and IFN-r in host's serum, as well as parasite antigens, which may act singly or in concert, in the process of enhanced erythrocyte destruction, hence anaemia by the mononuclear phagocytic system (MPS) during bovine trypanosomosis.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Haematological observations on helminthiasis caused by Haemonchus contortus in Nigerian dwarf sheep

The haematology of three groups, A, B and C, of unweaned lambs aged 2, 4 to 4½ and 5 to 6½ months respectively and their dams exposed to a natural outbreak of helminthiasis predominantly caused by Haemonchus contortus was studied prior to and after treatment with thiabendazole. Lambs of group A showed negative faecal egg counts and had normal red cell values and live weights. Lambs of groups B an C showed signs of severe parasitism including marked stunting and a normocytic normochromic anemia characterised by low packed cell volumes, low red cell counts and depressed haemoglobin concentrations; these lambs displayed marked individual variability in the effects of the disease, with very significant correlations (P < 0'01) between strongyle egg counts and red cell values. Severe anaemia was associated with a high reticulocyte response (2 to 16 per cent). Treatment with thiabendazole was followed by reduction of faecal egg excretion and significantly improved packed cell volumes and red cell counts but not haemoglobin concentration, as measured weeks later. The ewes were only mildly parasitised, with low faecal egg Counts and a mild depression of the red cell indices; these were slightly but significantly elevated following treatment. These findings are discussed in relation to observations in other parts of the world, to the Nigerian livestock management practices, and to the low hematological status commonly encountered in African livestock

Serum total proteins and creatinine levels in experimental gambian trypanosomosis of vervet monkeys

Although Human African Trypanosomosis presently constitute a major socio-economic problem in several parts of sub-Saharan Africa, conflicting reports on experiemental infections appear to be one of the factors limiting the chemotherapeutic control of the disease. Attempt was therefore made to evaluate the effect of two strains of Trypanosoma brucei gambiense on total proteins and other serum biochemical parameters using vervet monkeys as a model. The outcome of both strains in vervet monkeys was traumatic as the monkeys died from infection 12 - 15 weeks post infection while the serum total proteins increased due to increase in serum globulins with resultant fall in the albumin/globulin ratio. Similarly creatinine and fibrinogen levels increased after infection. The study confirms the existence of atypical virulent infections with a resultant early death from T. b. gambiense

The role of the bone marrow in bovine trypanotolerance. 1. Changes in blood and bone marrow in Trypanosoma congolense-infected cattle

This study compared the changes in the bone marrow (BM) of five trypanotolerant N'Dama cattle with those of four trypanosusceptible Boran cattle during trypanosome infection. In the early parasitaemic phase, from 12 to 21 days postinfection (DPI), tsetse transmitted primary Trypanosoma congolense IL 1180 infection induced parasitaemia, slight depression in packed cell volume (PCV), marked leucopenia due to lymphocytopenia and eosinopenia, and thrombocytopenia which were of similar intensity in Boran and N'Dama cattle. However, from 28 DPI until the end of the experiment on 112 DPI, the parasitaemia was higher in the Boran than in the N'Dama. Severe anaemia and leucopenia characterised by lymphopenia, neutropenia, eosinopenia and monocytopenia persisted in Boran cattle. In contrast, the PCV values dropped gradually in N'Dama cattle and from 77 DPI recovered slowly to values just below preinfection levels by 112 DPI. The total and differential leucocyte counts of the N'Dama cattle stabilised at approximately two thirds of preinfection values between 28 and 112 DPI, and were double those of the Boran. Marked thrombocytopenia occurred in both breeds. The anaemia was initially macrocytic hypochromic but terminally became microcytic hypochromic in both breeds. Light and electron microscopic studies of sequential biopsies of the BM of these animals showed that the BM response was the key to these differences between the N'Dama and Boran. The biopsies of the BM of the N'Dama cattle were hypercellular (scored 4.5 ± 1.0 compared to 4.0 for controls) with mild hyperplasia of erythroid cells and mild hypoplasia of myeloid cells from 28 to 112 DPI, endowing the animals with higher haemopoietic potential that enabled them to replace most lost cells. In contrast, the Boran cattle had hypocellular (scored 2.4 ± 1.1) BM biopsies with relative erythroid hyperplasia and myeloid hypoplasia, resulting in low capacity of cell replacement manifested as severe unremitting anaemia and leucopenia. The BM of both breeds showed moderate hyperplasia of cells of the mononuclear phagocyte system. Therefore, this study showed, for the first time, that BM response is a key determinant factor of trypanotolerance as it determines the animal's capability for blood cell regeneration

Bone marrow and macrophage functions as determinants of bovine trypanotolerance

Sequential changes in the blood and bone marrow (BM) were studied by light and transmission electron microscopy in three Boran and three Ndama cattle before and after a primary infection with Trypanosoma congolense IL 1180. Parasitaemia was essentially similar in the Borans and the Ndamas between day 11 post-infection (DPI) and 59 DPI. Thereafter, until 112 DPI when the study was terminated, parasitaemia was higher in the Boran than in the Ndama. During the acute phase, the infection induced anaemia and leucopaenia which were milder in the Ndama than in the Boran. In the chronic phase, the leucocyte numbers and PCV of the Ndama improved, approaching pre-infection levels, whereas the values for the Boran continued to drop. Moderate thrombocytopaenia developed in the two breeds of cattle with no remarkable differences between them. The cellularity of BM biopsies were similar in the two breeds before infection. Following infection, the BM biopsies of Ndama cattle were consistently hypercellular while those of the Boran were hypocellular. The infection caused marked erythroid hyperplasia with marked hypoplasia of granulocyte elements in the Boran while there were only moderate corresponding shifts in these cell lineages in the Ndama. There was moderate hyperplasia of macrophages (Mo) in the bone marrow of both breeds, and the calculated volume index of Mo was 19.5 (+ or -) 3.6 in the Boran and 33.2 (+ or -) 3.9 in the Ndama (D<0.005) compared to 5.3 (+ or -) 1.4 and 4.7 (+ or -) 0.6 respectively, before infection. The Mo of both breeds were activated as shown by their significantly increased sizes and organelle (mitochondria, ER) contents, but those of the Ndama were more activated. The Mo in the BM phagocytosed immature and mature haemopoietic cells in the BM pariticulary erythrocytes, granulocytes and thrombocytes and smaller numbers of lymphoid cells and monocytes. Cells phagocytosis was preceded by cell to Mo attraction, and then adhesion. Prior to infection, the Mo had contacts with haemopoietic cells through V- or U-shaped microvilli apparently associated with Mo control of haemopoiesis; these contacts increased during infection. Target cell adhesion to Mo and phagocytosis, and contacts with haemopoietic cells were more marked with Mo of the Ndama than in the Boran, and these activities were further reduced in the boran on 98 and 112 DPI. In conclusion, it would appear that the Ndama achieve this superior tolerance because of hypercellularity of the BM and the greater activation of the Mo which result in greater haemopoiesis. Since cytophagia was also greater in the Ndama, our results indicate that this breed produces more blood cells and destroys more than the Boran. The balance between production and destruction appears to be much greater in the Ndama than in the Boran. The results of this study show that the BM is the key determinant organ of trypanotolerance in cattle while the Mo, particularly those of the BM, form the pivot of this control

The haematology of Trypanosoma congolense infection in cattle. II. Macrophage structure and function in the bone marrow of Boran cattle

Macrophages (Mo) in smears and sections of sternal bone marrow (BM) derived by weekly sequential biopsies from five adult Boran cattle re-challenged with Trypanosoma congolense were studied by light and transmission electron microscopy (TEM). Cells of the mononuclear phagocyte system including monoblasts, promonocytes, monocytes and Mo increased several fold in the sinusoids and haemopoietic compartment (HC) of the BM during infection. Mo activation occurred with significant increases (p<0.001) in Mo size and numbers of organelles including mitochondria, lysosomes and rough endoplasmic reticulum. Light microscopic examination of the BM smears showed that 25.8 percent of 1200 Mo examined phagocytosed many non-mitotic harmopoietic cells of the erythroid and granulocytic series as well as mature erythrocytes and thrombocytes but seldom lymphocytes from day 29 postinfection (dpi), when the first peak of parasitaemia occurred, until and termination of the experiment on 98 dpi. Some of the Mo with phagocytosed cells (10.4 percent) had cells from more than one lineage. TEM confirmed cytophagia and showed that the process begins with cell to Mo attraction characterised by development of microvilli at the surface of contact by the target cell and of envoloping pseudopodia by the Mo. This was followed by target cell to Mo adhesion and finally phagocytosis. The cells being phagocytosed and those freshly engulfed appeared morphologically normal. Many Mo were heavily laden with haemosiderin in the chronic phase of the infection (78 and 98 dpti). TEM showed that the activated Mo in the BM developed extensive contacts through reciprocal blunt microvilli with the haemopoietic cells. Macrophages were absent from the sinusoids of the BM prior to infection but became numerous during infection, and were adhered to sinusoidal endothelial cells by reciprocal blunt microvilli. These Mo phagocytosed blood cells (erythrocytes, neutrophils, thrombocytes), and free trypanosomes which, though present in the arterioles of the BM, were never seen in the sinusoids and HC of the BM. This study indicates that the Mo plays very vital roles in regulating and executing the events in the BM during T. congolense infection of cattle