Antigen-specific IL-2 secretion correlates with NK cell responses after immunization of Tanzanian children with the RTS,S/AS01 malaria vaccine.

Journal article

RTS,S/AS01, a vaccine targeting pre-erythrocytic stages of Plasmodium falciparum, is undergoing clinical trials. We report an analysis of cellular immune response to component Ags of RTS,S-hepatitis B surface Ag (HBs) and P. falciparum circumsporozoite (CS) protein-among Tanzanian children in a phase IIb RTS,S/AS01(E) trial. RTS,S/AS01 (E) vaccinees make stronger T cell IFN-γ, CD69, and CD25 responses to HBs peptides than do controls, indicating that RTS,S boosts pre-existing HBs responses. T cell CD69 and CD25 responses to CS and CS-specific secreted IL-2 were augmented by RTS,S vaccination. Importantly, more than 50% of peptide-induced IFN-γ(+) lymphocytes were NK cells, and the magnitude of the NK cell CD69 response to HBs peptides correlated with secreted IL-2 concentration. CD69 and CD25 expression and IL-2 secretion may represent sensitive markers of RTS,S-induced, CS-specific T cells. The potential for T cell-derived IL-2 to augment NK cell activation in RTS,S-vaccinated individuals, and the relevance of this for protection, needs to be explored further.

Authors: Horowitz, A; Hafalla, J; King, E; Lusingu, J; Dekker, D

• Publication status: Published
• Journal: Journal of Immunology
• Volume: 188
• Issue: 10
• Pages: 5054-5062
• Publication date: 2012-05-01
• DOI: 10.4049/jimmunol.1102710
• EISSN: 1550-6606
• ISSN: 0022-1767
• Language: English
• Keywords: Killer Cells, Natural; Malaria Vaccines; Epitopes; Biological Markers; Plasmodium falciparum; Humans; Protozoan Proteins; Infant; Cells, Cultured; Kenya; Lymphocyte Activation; T-Lymphocyte Subsets; Tanzania; Interleukin-2