Abstract

Naturally acquired immunity to Plasmodium falciparum is related to
immune system that changes during normal development
and ageing. The effects of repeated infections during the early life on
the maturation of the immune system are still unknown.
Elucidation of these effects is of considerable interest given that
malaria originates high mortality, especially during the first years
of life.

We conducted a cohort study to identify naturally acquired immune
responses to P. falciparum. Cellular responses of Cameroonian
neonates from birth to 36 months of age were evaluated every 6 months by
cell proliferation and cytokines (IFN- , IL-2 and IL-4)
production after in vitro culture in the presence of schizont extract
and Pf155/RESA peptides.

Data were analyzed by a multiple correspondence analysis (MCA)
exhibiting three main findings. Firstly, the lack of timedependant
evolution of specific immune pathways recruitment in the response to a
given antigen, no antigen inducing a specific
mode of response at a given time-point. Secondly, most of the data
variability was expressed by IFN-  and IL-4 productions, and
the major variation of the immune response with age involved this change
in IFN-  production. Thirdly, the age-related immune
response evolution is characterized by the acquisition of the capacity
to mount a IFN-  response, a transient phase during which
children produce a high IL-4 response, and the fast vanishing of the
dominance of the IL-2 response. These results suggest that P.
falciparum specific immune responses are first oriented towards a
Th2-type of response, and later switch to Th1-type of response.
© 2006 Elsevier B.V. All rights reserved.

Keywords: Plasmodium falciparum; Children; Cytokines; Immunity