[Role of spleen cells in protection against malaria]

IMMUNITY: The anti-infectious effect of the spleen in general and its anti-malarial effect has been known for a long time. This effect is associated, among other functions, with the spleen's capacity to filter and destroy erythrocytes parasitized by plasmodies or altered by various physical (heat...) or chemical factors. In addition, splenic immunity, which associates specific and nonspecific humoral and cellular effector mechanisms is no longer a question of debate.

There remains nevertheless one aspect of the question to be elucidated: the probable interaction between this immunity and other (genetic...) factors of the malarious host. CELL FUNCTIONS: This article summarizes current knowledge in connection with: a) participation of various cell populations in the mechanisms of splenic filtration and phagocytosis and b) genesis of a repertory of B and T lymphocytes, plasmodio-specific memory cells. During an infection, lymphocytes, monocytes and macrophages are recruited from peripheral blood and, in cooperation with cells known as "barrier" cells, increase the capacity of splenic filtration/purge and phagocytosis. In addition, the appearance of B and T lymphocytes with specific memory of P. falciparum result from hypermutation in VH genes (for B lymphocytes) or from clonal selection (for T lymphocytes). The folicular dendritic cells accomplish a reserve function. By constantly releasing the antigen, these cells would contribute to maintaining immune memory or to stimulating naive cells. Further studies are necessary to better understand the role of the splenic microcirculation and to identify parasite components which stimulate the protective response of the spleen against plasmodies.