Logo image
Plasmodium-host interactions directly influence the threshold of memory CD8 T cells required for protective immunity
Journal article   Peer reviewed

Plasmodium-host interactions directly influence the threshold of memory CD8 T cells required for protective immunity

Nathan W Schmidt, Noah S Butler and John T Harty
The Journal of immunology (1950), Vol.186(10), pp.5873-5884
05/15/2011
DOI: 10.4049/jimmunol.1100194
PMCID: PMC3087867
PMID: 21460205

View Online

Abstract

Plasmodium infections are responsible for millions of cases of malaria and about one million deaths annually. Recently, we showed that sterile protection (95%) in BALB/c mice required P. berghei circumsporozoite (CS 252-260 )-specific memory CD8 T-cells exceeding a threshold of ≥1% of all PBL. Importantly, it is not known if Plasmodium species affect the threshold of CS-specific memory CD8 T-cells required for protection. Furthermore, C57BL/6 mice immunized with radiation attenuated parasites are more difficult to protect against Plasmodium sporozoite challenge than similarly immunized BALB/c mice, however, it is not known if this is the result of different CD8 T-cell specificity, functional attributes of CD8 T-cells or mouse strain-specific factors expressed in non-hematopoietic cells. Here, we show more CS-specific memory CD8 T-cells are required for protection against P. yoelii sporozoite challenge than for protection against P. berghei sporozoite challenge. Furthermore, P. berghei CS 252 -specific CD8 T-cells exhibit reduced protection against P. berghei sporozoite challenge in the context of C57BL/6 and C57BL/10 non-MHC-linked genes in CB6F1 and B10.D2 mice, respectively. Generation and immunization of reciprocal chimeric mice between BALB/c and B10.D2 strains revealed that B10 background factors expressed by non-hematopoietic cells increased the threshold required for protection through a CD8 T-cell extrinsic mechanism. Finally, reduced CS-specific memory CD8 T-cell protection in P. yoelii infected BALB/c or P. berghei infected B10.D2 mice correlated with increased rates of Plasmodium amplification in the liver. Thus, both Plasmodium species and strain-specific background genes in non-hematopoietic cells determine the threshold of memory CD8 T-cells required for protection.

Details

Metrics

Logo image