Interaction between HTLV-1 and Strongyloides stercoralis infection resulting in lowered IgE titres in Jamaica - abstract

ABSTRACT

In Japan, a positive association exists between the presence of serum antibodies to HTLV-1 and S. stercoralis. Also, it has been shown in Jamaica that coincidental HTLV-I infection may influence the outcome of treatment of S. stercoralis, or even underlie development of severe strongyloidiasis in some persons. However, the relationship between HTLV-I and S. stercoralis remains unclear. This paper highlights a hitherto unreported association between the occurrence of serum antibodies to HTLV-I, to S. stercoralis, and total serum IgE and strongyloidiasis in a Jamaican community. Blood and stool samples were collected from 67 persons from 6 geographical locations in Kingston. Sera were analysed for antibodies to S. stercoralis and HTLV-I, while stool samples were subjected to charcoal coproculture. As in Japan, individuals serologically positive for S. stercoralis tended to be infected more often with HTLV-I (33 per cent) than seronegative individuals (15 per cent), but the difference was not significant (two-tailed Fisher's exact test; P = 0.15). However, parasitologically-proved strongyloidiasis and HTLV-I seroconversion were strongly associated; while occurrence of HTLV-I was 67 per cent in individuals whose stool contained S. stercoralis larvae, it was only 15 per cent in their parasitologically negative counterparts (two-tailed Fisher's exact test; P = 0.01). Analyses strongly suggest that serological status for S. stercoralis HTLV-I affect IgE titres interaction term, F = 3.54; P = 0.06). IgE titres were lower in HTLV-I seropositive than seronegative individuals in both groups with and without S. stercoralis antibodies (HTLV-I main effect, F = 11.13; P = 0.002), but more strongly so in the former group (Table). S. stercoralis infection appeared to elevate reagin levels in some individuals in the HTLV-I negative group (n=13) (one-way ANOVA, F = 2.09; P - 0.15). In contrast, however, serum IgE titres were depressed in the group (n-5) with HTLV-I and concomitant S. stercoralis infection to levels perhaps even lower than those seen in HTLV-I individuals who did not have S. stercoralis (one-way ANOVA, F = 2.39; p = 0.15). Thus, it appears that HTLV-I and S. stercoralis operate synergistically to effect a significant reduction in IgE serum antibodies in infected individuals. If expressed at the level of the intestinal mucosa, this may permit increased rates of autoinfection of the parasite and result in correspondingly greater worm loads and patient morbidity. Lower levels of IgE antibodies against S. stercoralis are known to be associated with disseminated disease (AU)