Activation of gammadelta T cells in malaria: interaction of cytokines and a schizont-associated Plasmodium falciparum antigen.
A soluble Plasmodium falciparum antigen that specifically stimulates gammadelta T cells has been found associated predominantly with schizonts rather than ring forms, trophozoites, or gametocytes. This schizont-associated antigen (SAA) is resistant to protease digestion, is anionic at pH 8.5, is heat- and pH-resistant, and contains a phosphate group(s) that is crucial for biologic activity. Partially purified SAA induced proliferative responses and interferon-gamma production by gammadelta T cells. These stimulatory effects were greatly enhanced by monocyte-derived cytokines, interleukin (IL)-10, IL-12, and IL-1beta, but not by tumor necrosis factor-alpha. Taken together, these results suggest that concurrent stimulation of gammadelta T cells by SAA and by cytokines released from activated monocytes (IL-10, IL-12, IL-1beta) may represent the major mechanism underlying the selective activation of gammadelta T cells that is consistently observed in clinical cases of P. falciparum infection.
Pichyangkul
S
S
Department of Immunology and Medicine, US Army Medical Component, AFRIMS, Bangkok, Thailand.
Saengkrai
P
P
Yongvanitchit
K
K
Stewart
A
A
Heppner
D G
DG
D000328:Adult; D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology*; D016207:Cytokines / Q000502:physiology*; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D008213:Lymphocyte Activation; D016778:Malaria, Falciparum / Q000276:immunology*; D010963:Plasmodium falciparum / Q000276:immunology; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000032:analysis*; D013601:T-Lymphocytes / Q000276:immunology*
D000953:Antigens, Protozoan; D016207:Cytokines; D016692:Receptors, Antigen, T-Cell, gamma-delta; D007371:Interferon-gamma