Plasmodium falciparum: characterization of toxin-associated proteins and identification of a hemoglobin containing parasite cytokine stimulator

TY - JOUR

T1 - Plasmodium falciparum: characterization of toxin-associated proteins and identification of a hemoglobin containing parasite cytokine stimulator

AU - Kristensen, G

AU - Jakobsen, P H

N1 - Keywords: Animals; Antigens, Protozoan; Autoradiography; Cytokines; Electrophoresis, Polyacrylamide Gel; Hemoglobins; Immune Sera; Immunoblotting; Mice; Plasmodium falciparum; Precipitin Tests; Protozoan Proteins; Toxins, Biological

PY - 1996

Y1 - 1996

N2 - Previous studies have indicated the inositol monophosphate (IMP) is a component of the malaria parasite toxin that induces cytokines such as tumour necrosis factor (TNF). To further characterize the toxin we have labeled Plasmodium falciparum in vitro cultures with [14C]inositol or [35S]-methionine and immunoprecipitated the labeled antigens with an antiserum against IMP which blocks malaria parasite-induced TNF production. We detected four proteins associated with IMP when the immunoprecipitates were separated by SDS-PAGE and analyzed by autoradiography. To evaluate the capacity of different P. falciparum antigens to induce cytokine production we separated a mixture of exoantigens by SDS-PAGE gels. Antigen fractions of 43-71 kDa and of a low molecular mass of <20 kDa contained the dominant inducers of TNF alpha interleukin 1 alpha, and interleukin 6 production from human mononuclear cells. The low-molecular-mass antigen fraction contained hemoglobin, while no parasite-specific proteins were detectable when tested by immunoblotting. Hemoglobin may act as a carrier for cytokine-inducing malaria parasite toxins.

AB - Previous studies have indicated the inositol monophosphate (IMP) is a component of the malaria parasite toxin that induces cytokines such as tumour necrosis factor (TNF). To further characterize the toxin we have labeled Plasmodium falciparum in vitro cultures with [14C]inositol or [35S]-methionine and immunoprecipitated the labeled antigens with an antiserum against IMP which blocks malaria parasite-induced TNF production. We detected four proteins associated with IMP when the immunoprecipitates were separated by SDS-PAGE and analyzed by autoradiography. To evaluate the capacity of different P. falciparum antigens to induce cytokine production we separated a mixture of exoantigens by SDS-PAGE gels. Antigen fractions of 43-71 kDa and of a low molecular mass of <20 kDa contained the dominant inducers of TNF alpha interleukin 1 alpha, and interleukin 6 production from human mononuclear cells. The low-molecular-mass antigen fraction contained hemoglobin, while no parasite-specific proteins were detectable when tested by immunoblotting. Hemoglobin may act as a carrier for cytokine-inducing malaria parasite toxins.

U2 - 10.1006/expr.1996.0019

DO - 10.1006/expr.1996.0019

M3 - Journal article

C2 - 8617341

SN - 0014-4894

VL - 82

SP - 147

EP - 154

JO - Experimental Parasitology

JF - Experimental Parasitology

IS - 2

ER -