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Inactivation or elimination of potentially trypanolytic, complement-activating immune complexes by pathogenic
Infection and Immunity
|June 1, 1979
Summary
Trypanosomes incubated with antibodies at lower temperatures are lysed by complement, while those at higher temperatures survive. This survival is linked to antigenic variation, impacting infectivity in mice.
Area of Science:
- Immunology
- Parasitology
- Molecular Biology
Background:
- Trypanosoma species are significant protozoan parasites causing diseases like sleeping sickness.
- Immune evasion strategies, including antigenic variation, are crucial for trypanosome survival.
- Antibody-mediated immunity and complement activation are key host defense mechanisms against trypanosomes.
Purpose of the Study:
- To investigate the effect of temperature on antibody-mediated lysis of Trypanosoma brucei and Trypanosoma congolense by complement.
- To determine the infectivity and antigenic properties of surviving trypanosomes after complement treatment.
- To explore the mechanisms of immune complex elimination and antigenic variation in trypanosomes.
Main Methods:
- Incubation of trypanosomes with homologous antibody at different temperatures (0°C and 37°C) followed by guinea pig complement treatment.
- Assessment of trypanosome lysis and survival rates.
- Infectivity assays in X-irradiated mice and mice immunized with homologous antigens.
- Serotype analysis of isolated trypanosome substrains.
Main Results:
- Trypanosomes incubated with antibody at 0°C were lysed by complement, whereas those incubated at 37°C remained intact.
- Survival proportion decreased with increasing antibody concentration.
- Surviving trypanosomes expressed antigens but lacked complement-activating immune complexes.
- Infectivity in mice was significantly higher for trypanosomes incubated at 37°C compared to 0°C.
- Evidence suggested that surviving T. brucei could undergo antigenic variation.
Conclusions:
- Temperature plays a critical role in antibody-dependent complement-mediated lysis of trypanosomes.
- Trypanosomes possess mechanisms to eliminate surface immune complexes, facilitating survival and antigenic variation.
- These mechanisms are vital for trypanosome persistence and pathogenesis in hosts, contributing to the challenge of treating trypanosomiasis.