IMMUNOPURIFICATION AND MEASUREMENT OF IGE IN SERUM SAMPLES FROM BANCROFTIAN FILARIASIS PATIENTS

Patent infection with Wuchereria bancrofti is associated with increase d levels of filaria-specific IgG4 and IgE. In vitro quantification of filaria-specific IgE is hampered by its small proportion in serum rela tive to other isotypes and by potential competition with IgG4 for the same epitopes on parasite antigens. To determine if IgG4 or other isot ypes inhibit the detection of parasite-specific IgE, total IgE was aff inity purified prior to filaria-specific IgE enzyme-linked immunosorbe nt assay. Briefly, anti-human IgE mouse monoclonal antibody 6H10 was c oupled to Affigel, and 50 mu l of patient serum was incubated on micro columns for 16 hr. Total IgE was eluted with 25 mM triethylamine (pH 1 1.2) and levels of total and filaria-specific IgE and total IgG4 were assessed in the filtrates and eluates. Sera from 14 patients with W. b ancrofti microfilaremia (Mf(+)) and 17 amicrofilaremic patients with c hronic pathology (CP) were assayed. Filtrates and eluates were devoid of IgE and IgG4, respectively. The average yield of total IgE in the e luates was 70% (SEM = 6.5; range 21-100%) of that measured in the seru m. Antifilarial IgE levels in column eluates were significantly higher in serum samples from CP patients than Mf(+) patients. Antibody inhib ition of IgE was assessed by comparing the levels of anti-filarial IgE detected in eluates and serum. Evidence for antibody-mediated inhibit ion of IgE detection was obtained with 2/2 samples from Indian tropica l pulmonary eosinophilia patients, but only 2/14 and 4/17 Mf(+) and CP patients, respectively.