HUMORAL RESPONSES IN HUMAN STRONGYLOIDIASIS - CORRELATIONS WITH INFECTION CHRONICITY

Strongyloides stercoralis L3-specific antibody isotype responses among st individuals with known longstanding (28-46 years) infection were co mpared with those of 'young' (6-29 years of age) and 'old' (30-80 year s of age) infected individuals from an endemic Jamaican population. Ch aracterization of age-dependent isotype patterns in the endemic commun ity showed that immunoglobulin (Ig) G1 responses were significantly in versely correlated with age. Additionally, a trend towards lower IgE l evels in the older age group was observed. Comparison with responses a mongst known chronically infected individuals showed that IgG1 and IgE levels were similar to those of the 'old' endemic group, but were sig nificantly lower than those of the 'young' group. In contrast, IgA lev els were similar in both endemic groups, but were elevated in chronica lly infected individuals. IgG4 levels were similar in all groups studi ed. These findings suggest that age correlates with infection chronici ty in communities endemic for S. stercoralis, and that individuals acq uire infection early in their lives and remain infected into adulthood . Early and sustained upregulation of IgG4 may facilitate the establis hment of infection and, in combination with developing IgE hyporespons iveness, may promote chronic asymptomatic strongyloidiasis. Conversely , upregulated IgA may be involved in controlling chronic infection lev els which are reflected in reduced IgG1 production.