ELEVATED ANTIFILARIAL IGG4 ANTIBODY-LEVELS IN MICROFILAREMIC AND MICROFILARIDERMIC GABONESE ADULTS AND CHILDREN

Immunologic analyses of sera from 47 selected individuals living in a mixed filariasis transmission zone in Gabon were carried out. Onchocer ca volvulus, Loa loa, Mansonella streptocerca, and M. perstans are tra nsmitted in this region. Based on parasitologic findings and age, the 47 individuals were stratified into four groups: microfilaria negative (Mf-) children (3-15 years old), Mf- adults (> 15 years old), microfi laria positive (Mf+) children and Mf+ adults. For descriptive purposes , the term microfilaria positive refers to individuals with skin and b lood microfilariae. Antifilarial antibody titers were determined using an enzyme-linked immunosorbent assay with Dipetalonema viteae antigen s. In general, children had higher titers of IgG antibodies than adult s. For the IgG 1, IgG2, and IgG3 subclass responses, both age and micr ofilarial status appeared to be important variables since Mf- children consistently had the highest titers whereas Mf- adults had the lowest titers. For the IgG4 antifilarial response, only the microfilarial st atus was an important variable. All Mf+ individuals had significantly higher levels of IgG4 antibody than Mf- individuals. Pooled sera of Mf - and Mf+ individuals reacted with similar O. volvulus antigens on Wes tern blots. Control sera of individuals who did not reside in the stud y area, but who had single infections with L. loa or M. perstans, did not react with any O. volvulus antigens.