Correlation of Plasmodium falciparum gametocytemia with complement component titers in rural Nigerian school children.

The relationship between Plasmodium falciparum gametocytemia and the complement components C3, C4, and C3b was investigated in 141 ambulant rural Nigerian school children. Three groups were studied. Group 1 included 42 children with circulating P. falciparum gametocytemia in which the mean titers of C3, C4, and C3b were 145.4 +/- 22.6 mg/100 ml (72%), 60.5 +/- 0.2 mg/100 ml (149%), and 64.0 +/- 5.9 mg/liter (65%), respectively. These findings indicated marked C3b hypocomplementemia. Group 2 included 50 children who were used as controls and lacked malaria parasitemia. C3, C4, and C3b mean titers were 161.6 +/- 28.9 mg/100 ml (80%), 56.8 +/- 2.07 mg/100 ml (140%), and 84.8 +/- 11.4 mg/liter (86%), respectively. Group 3 included 49 children with other blood stages of P. falciparum parasitemia but no gametocytes. C3, C4, and C3b mean titers in this group were 103.0 mg/100 ml (51%), 18.3 +/- 1.2 mg/100 ml (45%), and 90.7 mg/liter (92%), respectively. Our findings suggest that C3b hypocomplementemia may be related to the advent of circulating P. falciparum gametocytes in children. We also confirmed C3 and C4 hypocomplementemia in acute human malaria. The implication of our findings in relation to neat in vitro culture of P. falciparum gametocytes or total inhibition of gametocytogenesis in malaria control is still speculative.