MATERNAL ANTIBODIES AND ACQUIRED SEROLOGICAL RESPONSE TO MORAXELLA-CATARRHALIS IN CHILDREN DETERMINED BY AN ENZYME-LINKED-IMMUNOSORBENT-ASSAY

An enzyme-linked immunosorbent assay (ELISA) for determination of seru m immunoglobulin G(IgG) antibodies to Moraxella catarrhalis was develo ped, with an ultrasonic extract of M. catarrhalis immobilized on polys tyrene microtiter plates serving as the antigen. The specificity was d etermined by adsorption tests. All of the 541 women tested showed a hi gh level of maternal IgG antibodies to M. catarrhalis in umbilical cor d blood specimens. One hundred eighty-nine children aged 0 to 15 years were examined. A low level of IgG antibodies to M. catarrhalis in ser um was found in children aged up to 1 year; in older children, the lev els increased with age. Levels in the same range as maternal IgG antib ody levels were reached at the age of 10 years. The level of antibodie s in children did not correlate, with the state of colonization with M . catarrhalis or with the state of acute lower respiratory tract infec tion. Pairs of acute-phase and convalescent-phase serum samples did no t discriminate between the children with M. catarrhalis in pure cultur e and those with mixed cultures of M. catarrhalis, Haemophilus influen zae, and Streptococcus pneumoniae. In adult women, high IgG antibody l evels and low colonization rates with M. catarrhalis were found, where as in small children, low IgG antibody levels and high colonization ra tes were found.