IL-10 is up regulated in early and transitional stages in vervet monkeys experimentally infected with Trypanosoma brucei rhodesiense

Abstract

IL-10 has been suggested as a possible parameter for human African trypanosomiasis stage determination. However, conclusive experimental studies have not been carried out to evaluate this, which is a prerequisite before a potential test can be validated in humans for diagnostic purposes. We used the vervet monkey model of trypanosomiasis to scrutinize IL-I 0 in blood and cerebrospinal fluid (CSF). Five adult males were experimentally infected with T. b. rhodesiense. The infected animals became anaemic and exhibited weight loss. Parasitemia was patent after 3 days and fluctuated around 3.7 x 107 trypanosomes/ml throughout the experimental period. The total CSF white cell counts increased from pre-infection means around 3 cells to a peak of 30 cells/!!I, 42 days post-infection (DPI). IL IO was not detectable «2 pgfml) in serum prior to infection. IL-IO serum concentrations increased to 273 pgfml 10 DPI coinciding with the first peak of parasitemia. Thereafter the levels declined to a mean value of77 pgfml 34 DPI followed by a significant rise to a second peak of304 pgfml (p<O.008) 42 DPI. There was no detectable IL-IO in CSF. IL-IO synthesis is thus stimulated both in the early and transitional stages of experimental trypanosomiasis. That IL-IO is produced in early stage disease is an interesting finding unlikely to be detected in humans where it is difficult to determine the exact time of infection. The IL-l 0 peak observed on day 42 of infection might indicate onset of parasite neuroinvasion coinciding with a peak in white blood cell counts in the blood and CSF. © 2006 Elsevier Ireland Ltd. All rights reserved.