Effects of pregnancy and intensity of Plasmodium falciparum transmission on immunoglobulin G subclass responses to variant surface antigens.
Placenta-sequestering Plasmodium falciparum involved in the pathogenesis of pregnancy-associated malaria (PAM) in otherwise clinically immune women expresses particular variant surface antigens (VSA(PAM)) on the surface of infected erythrocytes that differ from VSA found in parasitized nonpregnant individuals (non-PAM type VSA). We studied levels of immunoglobulin G (IgG) and IgG subclasses with specificity for VSA(PAM) and for non-PAM type VSA in pregnant and nonpregnant women from two sites with different endemicities in Cameroon. We found that VSA(PAM)-specific responses depended on the pregnancy status, parity, gestational age, and parasite transmission intensity, whereas only the parasite transmission intensity influenced the levels of IgG specific for non-PAM type VSA. For both types of VSA, the responses were dominated by the cytophilic subclass IgG1, followed by IgG3. In pregnant women, the levels of VSA(PAM)-specific antibodies either were very low or negative or were very high, whereas the levels of the antibodies specific for non-PAM type VSA were uniformly high. Interestingly, the levels of VSA(PAM)-specific IgG1 increased with increasing gestational age, while the levels of the corresponding IgG3 tended to decrease with increasing gestational age. The IgG subclass responses with specificity for non-PAM type VSA did not vary significantly with gestational age. Taken together, our data indicate that IgG1 and to a lesser extent IgG3 are the main subclasses involved in acquired VSA(PAM)-specific immunity to pregnancy-associated malaria.
Megnekou
Rosette
R
Center for Medical Parasitology, Department of Infectious Diseases M7641, Copenhagan University Hospital (Rigshospitalet), Blegdamsvej 9, 2100 Copenhagen Ø, Denmark.
Staalsoe
Trine
T
Taylor
Diane W
DW
Leke
Rose
R
Hviid
Lars
L
D000293:Adolescent; D000328:Adult; D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000276:immunology*; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000145:classification*; D018445:Infectious Disease Transmission, Vertical; D016778:Malaria, Falciparum / Q000276:immunology*; D008875:Middle Aged; D015999:Multivariate Analysis; D010298:Parity; D011247:Pregnancy; D015597:Pregnancy Complications, Parasitic / Q000276:immunology*
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007074:Immunoglobulin G