Promiscuous malaria peptide epitope stimulates CD45Ra T cells from peripheral blood of nonexposed donors.
PBL from individuals with no history of malaria exposure, as well as cord blood lymphocytes, were tested for proliferation to T cell epitopes from the malaria circumsporozoite proteins of Plasmodium falciparum and Plasmodium vivax. Cells from many individuals proliferated in response to these peptides, but for two peptides (P. vivax317-336 and P. falciparum CS331-350) the response rate ranged from 64 to 93%, with the specific stimulation indices reaching as high as 38. The phenotype of the cells responding to PfCS331-350 was predominantly CD4+,CD8-,CD45Ra+,CD45Ro-, which was the inverse of the phenotype of the cells responding to tetanus toxoid with respect to CD45 isoforms. T cell clones from different individuals specific for PfCS331-350 were restricted by at least four different HLA-DR molecules and there was no evidence that the peptide was a "superantigen." Overlapping peptides were used to demonstrate that clones had different fine specificities although the peptide specificities of the DR4-restricted and DR11-restricted clones were similar. Although the individuals tested here have had no history of malaria exposure, these data demonstrate that they have T cells specific for malaria sequences present in high frequency that proliferate as intensely as some memory responses. Although one clone from an individual with a history of BCG vaccination did react strongly with PPD, the phenotype of these cells suggests that they are not classical memory cells for a cross-reactive recall Ag. Such cells may affect the induction or expression of malaria immunity.
Molecular Immunology Laboratory, Queensland Institute of Medical Research, Brisbane, Australia.
J
J
Fern
M F
MF
Good
D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000032:analysis*; D000953:Antigens, Protozoan / Q000737:chemistry / Q000276:immunology*; D000939:Epitopes; D006649:Histocompatibility Antigens / Q000032:analysis*; D006801:Humans; D017493:Leukocyte Common Antigens; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D010963:Plasmodium falciparum / Q000276:immunology*; D010966:Plasmodium vivax / Q000276:immunology*; D015800:Protozoan Proteins; D013601:T-Lymphocytes / Q000276:immunology*
D015703:Antigens, CD; D000953:Antigens, Protozoan; D000939:Epitopes; D006649:Histocompatibility Antigens; D010455:Peptides; D015800:Protozoan Proteins; C041595:circumsporozoite protein, Protozoan; D017493:Leukocyte Common Antigens