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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, METHODS, RESULTS. Meshes: Adolescent, Adult, Biomarkers, CD4-Positive T-Lymphocytes, CD8-Positive T-Lymphocytes, Female, Flow Cytometry, Healthy Volunteers, Humans, Leukocytes, Mononuclear, Malaria Vaccines, Malaria, Falciparum, Male, Plasmodium falciparum, Sporozoites, T-Lymphocytes, Cytotoxic, Treatment Outcome, Young Adult.
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Do cytotoxic markers associate with protection against malaria in human volunteers immunized with Plasmodium falciparum sporozoites? Context: 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. 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. 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.
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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. Final Decision: yes