Effect of recombinant malarial antigen on monocyte functionality.
Recombinant proteins and vaccine candidates of Plasmodium vivax have met with limited success. One of the reasons could be their effect on monocytes which are important in malaria pathogenesis. Our aim was therefore to investigate the effect of selected recombinant malarial proteins on monocytes functions.



Phagocytosis rate and respiratory burst of healthy individuals' monocytes treated with antigens were examined. The homing capacity of monocytes was studied by examining the mRNA level of chemokine receptors from patients and healthy individuals.



Phagocytosis rate was reduced in antigen treated monocytes whereas nitroblue tetrazolium (NBT) reduction was more in apical membrane antigen-1 (AMA-1) and merozoite surface protein-7 (MSP7) treated than in untreated and von Willebrand factor A domain-related protein (WARP) treated monocytes. Patient monocytes showed higher mRNA expression for CCR2 and CX3CR1 and reduced levels for CCR7 and CXCR4. AMA-1 and WARP treated monocytes showed lower expression for CCR2, CX3CR1 and CXCR4, but unchanged for CCR7. However, with MSP7, all the receptor levels were reduced. CX3CR1 in monocytes from activated PBMCs was either unchanged (AMA-1) or increased (MSP7, WARP) while remaining receptors were reduced.



These antigens may modulate the monocyte functionality and hence may not have desired therapeutic effect.
Department of Microbiology and Biotechnology Centre, Faculty of Science, The M. S. University of Baroda, Vadodara- 390 002, Gujarat, India.
Abhik
A
Saha
Department of Microbiology and Biotechnology Centre, Faculty of Science, The M. S. University of Baroda, Vadodara- 390 002, Gujarat, India.
Sejal
S
Chauhan
Department of Microbiology and Biotechnology Centre, Faculty of Science, The M. S. University of Baroda, Vadodara- 390 002, Gujarat, India. mailforbagchi@yahoo.com.
Tamishraha
T
Bagchi
D000953:Antigens, Protozoan / Q000276:immunology*; D006801:Humans; D008288:Malaria / Q000188:drug therapy / Q000276:immunology* / Q000469:parasitology; D017780:Malaria Vaccines / Q000276:immunology*; D008565:Membrane Proteins / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects* / Q000502:physiology; D009580:Nitroblue Tetrazolium; D010587:Phagocytosis / Q000187:drug effects*; D010966:Plasmodium vivax / Q000378:metabolism*; D015800:Protozoan Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D054390:Receptors, CCR2 / Q000378:metabolism; D054400:Receptors, CCR7 / Q000378:metabolism; D054387:Receptors, CXCR / Q000378:metabolism; D019707:Receptors, Chemokine / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D016897:Respiratory Burst
D000953:Antigens, Protozoan; D017780:Malaria Vaccines; D008565:Membrane Proteins; D015800:Protozoan Proteins; D012333:RNA, Messenger; D054390:Receptors, CCR2; D054400:Receptors, CCR7; D054387:Receptors, CXCR; D019707:Receptors, Chemokine; D011994:Recombinant Proteins; D009580:Nitroblue Tetrazolium
Apical membrane antigen-1; Malaria; Merozoite surface protein-7; Monocyte; Warp protein