TR1 Cells Lead the Fight Against Malaria | 31 May 2025

Source: TH 

Why in News? 

A new study has revealed that TR1 (Type-1 Regulatory T-cells), rather than TH1 cells, are the main drivers of the immune response to malaria, challenging earlier assumptions.

What are TR1 Cells? 

• About: TR1 cells, or Type-1 Regulatory T-cells, are a specialized group of CD4+ helper T-cells that play a key role in regulating the immune system.  
  • Unlike other T-cells that mainly attack pathogens, TR1 cells help control and balance immune responses by reducing inflammation and preventing excessive immune reactions.  
  • CD4+ cells (helper T cells) are a type of white blood cell (lymphocyte) that play a central role in adaptive immunity. They express the CD4 protein on their surface and help coordinate the immune response. 
• Role Against Malaria: When infected by Plasmodium falciparum, the body must balance fighting the parasite and avoiding excessive immune damage.  
  • TR1 cells promote immune tolerance by controlling inflammation, allowing coexistence with the parasite and helping develop clinical immunity that prevents severe illness.  
  • Essentially, TR1 cells act as peacekeepers, moderating the immune response to protect the body.

What are the Key Components of the Human Immune System? 

• Physical Barriers: These include the skin and mucous membranes that act as the first line of defense by preventing pathogens from entering the body. 
• Innate Immunity: This is the immediate, non-specific defense mechanism that includes physical barriers, white blood cells like neutrophils, macrophages, and natural killer cells, as well as the inflammatory response (such as swelling and fever).  
  • It provides rapid protection against any invading pathogens. 
• Adaptive Immunity: A slower but highly specific defense system that targets particular pathogens and creates memory for long-term protection. It involves specialized cells called lymphocytes, mainly B-cells and T-cells. 
  • B-cells: B-cells produce antibodies, which are proteins that bind specifically to antigens (foreign molecules on pathogens) to neutralize or mark them for destruction. 
  • T-cells: T-cells develop in the thymus and include: 
    • Helper T cells: Activate B-cells to produce antibodies, assist macrophages in killing microbes, and stimulate killer T cells. 
    • Killer T cells: Destroy virus-infected cells, cancer cells, and damaged cells. 
    • Regulatory T cells: Help control and balance the immune response. 
• Lymphatic System: Organs like lymph nodes, spleen, thymus, and bone marrow produce and house immune cells, filtering out pathogens and coordinating immune responses. 
• Chemical Messengers: Molecules like cytokines help immune cells communicate and regulate the body’s defense mechanisms. 

What is Malaria? 

• About: Malaria is a life-threatening vector-borne disease caused by the Plasmodium parasites, transmitted through the bites of infected female Anopheles mosquitoes. 
  • There are 5 Plasmodium parasite species that cause malaria in humans and 2 of these species – P. falciparum and P. vivax – pose the greatest threat. 
• Transmission: The mosquito becomes infected after biting an infected person. The malaria parasites then enter the bloodstream of the next person the mosquito bites.  
  • The parasites travel to the liver, mature, and then infect red blood cells. 
• Treatment:  
  • Artemisinin-based Combination Therapies (ACTs): It is the most effective treatment for Plasmodium falciparum malaria, combining artemisinin with another antimalarial drug. 
  • Chloroquine: It is used primarily for Plasmodium vivax and other non-falciparum malaria where resistance is not present. 
  • Primaquine: It is used to eliminate dormant liver forms (hypnozoites) of P. vivax and P. ovale to prevent relapse. 
  • Other Drugs: Such as quinine, mefloquine, and doxycycline, used in specific cases or drug-resistant infections. 
• Vaccine: The RTS,S/AS01 malaria vaccine, known as Mosquirix, became the first malaria vaccine to receive a World Health Organization (WHO) recommendation. 
  • The Serum Institute of India (SII), in collaboration with the University of Oxford, has developed a malaria vaccine called R21/Matrix-M, which has been recommended by WHO for use in malaria-endemic regions.   
• India’s Efforts to Contain Malaria: National Framework for Malaria Elimination 2016-2030, National Vector-Borne Disease Control Programme, National Malaria Control Programme (NMCP), Malaria Elimination Research Alliance-India (MERA-India).