Anti-malaria antibody-producing B cell frequencies in adults after a Plasmodium falciparum outbreak in Madagascar.
The central highlands of Madagascar offer a unique opportunity to explore the malaria immune memory, as the last murderous epidemic in the study area occurred 8 years ago. Quantification of the circulating memory B lymphocytes reacting to Plasmodium falciparum was assessed among 14 Madagascans by using a limiting dilution assay, applied to the EL4 culture system, which leads to activation, proliferation and differentiation into antibody-secreting cells (ASC) of most peripheral B cells. This system allowed us to observe, without any malaria-specific restimulation, a geometric mean frequency of one anti-P. falciparum ASC among 2992 circulating B cells, except for one Madagascan who did not have any detectable ASC. A geometric mean frequency of one anti-P. falciparum ASC among 1403 was obtained for six malaria hyperimmune Cameroonians, but conversely, no anti-malaria ASC was detected in the blood of six malaria non-immune French control subjects. Anti-P. falciparum ASC frequencies and serum specific antibodies were strongly related. Our results indicate that anti-malaria ASC are still present in peripheral blood of Madagascan subjects, who have not been exposed to P. falciparum for several years. These responder B cells reflect the malaria B cell memory acquired during the last epidemic.
INSERM U13/Institut de Médecine et d'Epidémiologie Africaines, Paris, France.
F
F
Migot
C
C
Chougnet
D
D
Henzel
B
B
Dubois
R
R
Jambou
N
N
Fievet
P
P
Deloron
D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan / Q000096:biosynthesis*; D001402:B-Lymphocytes / Q000276:immunology*; D004196:Disease Outbreaks; D006801:Humans; D007156:Immunologic Memory; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000276:immunology*; D008875:Middle Aged; D010963:Plasmodium falciparum / Q000276:immunology*
D000913:Antibodies, Protozoan