Antigen-reactive gamma delta T cells in human leishmaniasis.
The importance of Ag-specific gamma delta T lymphocytes in human immune responses to pathogenic organisms is unknown. In the present study the expression of gamma delta TCR on T lymphocytes from patients with cutaneous, mucosal, or visceral leishmaniasis was examined. All of these patient groups had elevated levels of gamma delta T cells in peripheral blood. Patients' gamma delta T cells included CD8+ as well as null cells. The percentage of T cells expressing gamma delta TCR was increased significantly by stimulation in vitro with certain parasite Ag. T-cell lines generated by stimulation with promastigote lysates of Leishmania amazonensis or L. braziliensis typically contained 25 to 60% gamma delta T cells. In contrast, two immunodominant surface Ag of L. amazonensis, gp63 and gp42, did not expand gamma delta T cells from infected patients, although both Ag elicited strong alpha beta T-cell responses. gamma delta T cells isolated from a Leishmania-specific T-cell line responded to stimulation with promastigote lysate. Of particular interest, gamma delta T cells from PBMC of a patient with mucosal leishmaniasis responded to stimulation with a recombinant 70 kDa heat shock protein of L. chagasi. This study demonstrated that several clinical forms of leishmaniasis induced elevated numbers of gamma delta T cells that responded specifically to Leishmania Ag in vitro. Therefore, this component of the T-cell response to Leishmania may impact the outcome of clinical disease.
Seattle Biomedical Research Institute, Washington 98109.
D M
DM
Russo
R J
RJ
Armitage
M
M
Barral-Netto
A
A
Barral
K H
KH
Grabstein
S G
SG
Reed
D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology*; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D002460:Cell Line; D006801:Humans; D007891:Leishmania / Q000276:immunology*; D007892:Leishmania braziliensis / Q000276:immunology; D007894:Leishmania mexicana / Q000276:immunology; D007896:Leishmaniasis / Q000276:immunology*; D008213:Lymphocyte Activation; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000032:analysis*; D013601:T-Lymphocytes / Q000276:immunology*
D000953:Antigens, Protozoan; D015704:CD4 Antigens; D016827:CD8 Antigens; D016692:Receptors, Antigen, T-Cell, gamma-delta