Possible role of specific immunoglobulin M antibodies to Plasmodium falciparum antigens in immunoprotection of humans living in a hyperendemic area, Burkina Faso

Abstract

Two seroepidemiological studies were performed in an area of Burkina Faso hyperendemic for malaria to estimate the protective role of immunoglobulin M (IgM) antibodies. Six cross-sectional surveys were carried out on children (ages, <16 years) in the village of Karankasso. The evolution of antibodies to crude extracts of Plasmodiumfalciparum (IgG or IgM antisomatic and IgG antiexoantigens) were tested by IFI or enzyme-linked immunosorbent assay and were followed up according to the fluctuations of the parasite densities. Specific IgG antibodies had the same evolution as parasite densities. By contrast, specific IgM antibodies increased when IgG and parasite densities began to decrease (despite a high inoculation rate). A longitudinal survey of 77 children and adults was conducted in another village (Dafinso). In that study, clinical follow-up of the selected individuals allowed us to define three groups in the population. Children in group 1 were considered nonimmune (children with one or more malaria attacks). Group 2 was composed of semiimmune children who did not present with any malarial attack during the survey but who had high levels of parasitemia during the transmission period. Group 3 was composed of immunoprotected adults. Specific IgM and IgG antibodies to crude extracts or a recombinant antigen (glutamate-rich protein) of P. falciparum were tested. Specific IgM

Distinct Interethnic Differences in Immunoglobulin G Class/Subclass and Immunoglobulin M Antibody Responses to Malaria Antigens but not in Immunoglobulin G Responses to Nonmalarial Antigens in Sympatric Tribes Living in West Africa

“…The elevated levels of these antibodies in the Fulani as compared with the non-Fulani suggest a protective role for the IgG as shown earlier and a similar role for the IgM antibodies. These findings are in line with previous reports that have suggested a protective role for IgM antibodies against malaria infection [27,28] or disease severity [29]. The fact that surface IgM þ B lymphocytes with long-lasting memory can persist after the malaria transmission season [30] may explain such elevated levels of P. falciparum-specific IgM in the Fulani.…”

Antibody Response Profiles Induced by Plasmodium Falciparum Glutamate-Rich Protein in Naturally Exposed Individuals From a Brazilian Area Endemic for Malaria

“…1 It is highly antigenic and the gene encoding GLURP shows little polymorphism in geographically different P. falciparum isolates. 2,3 Moreover, previous immunoepidemiologic studies performed in high transmission areas have shown a high prevalence of antibodies against GLURP in adults, [4][5][6] as well as a significant association of high levels of GLURP-specific antibodies with low parasite densities 7,8 and protection against clinical malaria. 6,[9][10][11] In addition, there has been evidence that cytophilic antibody responses to GLURP play a primary role in protection against P. falciparum malaria by effector mechanisms such as antibody-dependent cellular inhibition (ADCI), 12 the cooperation of monocytes and antibodies impairing parasite multiplication.…”

Plasmodium falciparum-specific IgM B cells dominate in children, expand with malaria and produce parasite inhibitory IgM

“…Several studies have reported Pf-specific IgM responses in malaria-exposed populations and in some cases have shown that these responses associate with protection from clinical malaria (9)(10)(11)(12)(13)(14)(15). For example, the malaria-resistant Fulani in West Africa have a higher breadth and magnitude of Pfspecific IgM compared to the more susceptible Dogon, whereas Pf-specific IgG did not distinguish the two groups (16,17).…”