Immune Reactions and Kinin Formation in Chronic Trypanosomiasis

Richards (1965) has shown that the concentration of kinins in the plasma and tissues of mice acutely infected with trypanosomes progressively increases until death occurs after 5 days.Kinins are also present in the urine of mice, rats and rabbits infected with Trypanosoma (Trypanozoon) brucei subgroup organisms (Goodwin & Richards, 1960; Boreham, 1966).It is possible that the kinin detected in the urine of infected animals may be derived from plasma proteins that have leaked through the kidneys because urinary kallikrein will release kinin from its precursor in plasma protein (Horton, 1959).If this is the case it is likely that urinary kinin is not important in the pathology of trypanosomiasis.Trypanosomiasis in rabbits, cattle and man follows a different course from that seen in laboratory rodents.Waves of parasitaemia occur at intervals of approximately 7-10 days and at no stage of the disease is the number of parasites in the blood large.In the rabbit this will continue for 5-6 weeks before death occurs but in cattle and man the disease process may continue for 1 or 2 years.Infected blood may be taken at any stage of the infection and the trypanosomes preserved by freezing.Such a preparation is called a stabilate.This term has been defined by Lumsden & Hardy (1965) as " a population of trypanosomes preserved in a viable condition on a unique occasion, and maintained at approximately -800 ".Trypanosomes in successive parasitaemic waves contain antigens which differ in their properties as shown by neutralization and agglutination reactions.These antigens are called the variant antigens (Lumsden, 1965).In addition other antigens are found which are common to all parasitaemic waves.These are called the common antigens and may be detected by the precipitin, fluorescence and complement fixation reactions.In order to understand more fully the disease processes which occur in chronic trypanosomiasis, work has been undertaken to investigate the level of kinins in the blood of infected rabbits and cattle, and to correlate their production with parasitaemia and the immunological response.