Format

Send to

Choose Destination
J Infect Dis. 2014 Nov 15;210(10):1605-15. doi: 10.1093/infdis/jiu293. Epub 2014 May 27.

Cytotoxic markers associate with protection against malaria in human volunteers immunized with Plasmodium falciparum sporozoites.

Author information

1
Department of Medical Microbiology.
2
Department of Infectious Diseases.
3
Department of Medical Microbiology, Department of Parasitology, Leiden University Medical Center, The Netherlands.
4
Department for Health Evidence, Section Biostatistics, Radboud university medical center, Nijmegen.

Abstract

BACKGROUND:

Immunization of healthy volunteers by bites from Plasmodium falciparum-infected mosquitoes during chloroquine chemoprophylaxis (hereafter, chemoprophylaxis and sporozoites [CPS] immunization) induces sterile protection against malaria. CPS-induced protection is mediated by immunity against pre-erythrocytic stages, presumably at least partially by cytotoxic cellular responses. We therefore aimed to investigate the association of CPS-induced cytotoxic T-cell markers with protection.

METHODS:

In a double-blind randomized controlled trial, we performed dose titration of CPS immunization followed by homologous challenge infection in 29 subjects. Immune responses were assessed by in vitro restimulation of peripheral blood mononuclear cells and flow cytometry.

RESULTS:

Dose-dependent complete protection was obtained in 4 of 5 volunteers after immunization with bites from 45 P. falciparum-infected mosquitoes, in 8 of 9 volunteers with bites from 30, and in 5 of 10 volunteers with bites from 15 (odds ratio [OR], 5.0; 95% confidence interval [CI], 1.5-17). Completely protected subjects had significantly higher proportions of CD4 T cells expressing the degranulation marker CD107a (OR, 8.4; 95% CI, 1.5-123; P = .011) and CD8 cells producing granzyme B (OR, 11; 95% CI, 1.9-212; P = .004) after P. falciparum restimulation.

CONCLUSIONS:

These data underline the efficiency of CPS immunization to induce sterile protection and support a possible role for cytotoxic CD4 and CD8 T-cell responses in pre-erythrocytic immunity.

CLINICAL TRIALS REGISTRATION:

NCT01218893.

KEYWORDS:

Plasmodium; T cells; chloroquine; cytotoxicity; degranulation; granzyme B; immunity; immunization; malaria; protection

PMID:
24872326
PMCID:
PMC4208622
DOI:
10.1093/infdis/jiu293
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Silverchair Information Systems Icon for PubMed Central
Loading ...
Support Center