Investigation of changes in immune responses in schistosomiasis patients co-infected with HIV following praziquantel treatment
Mutie-Mwinzi, Pauline Ngina
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Praziquantel (PZQ) efficacy and immune responses to schistosome antigens following cure were investigated in Schistosoma mansoni infected adult fishermen resident in Kisumu, Kenya with or without human immunodeficiency virus (HIV) co-infection. Schistosomiasis negative/HIV negative and schistosomiasis negative/HIV positive fishermen were used as controls. Proliferative responses to schistosome soluble egg antigen (SEA), soluble adult worm antigen preparation (SWAP), phytohaemagglutinin (PHA) and mycobacterium tuberculosis purified protein derivative (PPD) as well as leves of typical T helper-1 (TH-1) type, [gamma interferon (IFN-)] and T helper-2 (TH-2) type [Interleukin-4 (IL-4) and Interleukin-10 (IL-10)] cytokines were assayed at baseline, one month and four months post-treatment with Praziquantel. Indications of immunosuppression were determined by CD4+ counts and HIV testing by ELISA and Western blot. Cure success and reinfection rates were determined by longitudinal follow up of eggs per gram in stool using the Kato/Katz thick smear technique and the circulating cathodic antigen ELISA on plasma or serum. Among 190 fishermen examined, the intensity of egg excretion was found to be affected by HIV-1 serostatus, with HIV positive schistosomiasis patients excreting significantly lower numbers of eggs (x + SE = 251.47 + 105.97) than the HIV negative group (x + SE = 415.27 + 120.85) P<0.05, Mann Whitney U) although they had similar levels of CCA.. There was no significant difference in PZQ cure-success and cure rate between HIV positive and negative patients (P>0.05; Fishers exact test). More Patients responded to SWAP than to SEA and responses to SWAP were generally higher than those to SEA though insignificantly (P>0.05; Kruskall-Wallis). Schistosomiasis negative 0patients responded more to SWAP than their infected counterparts (Stimulation index E/C = 34+/- 13.7 and 13 +/- 2.7 respectively). The differences were not significant (P>0.05; Bonferroni multiple comparison test). HIV positive patients showed diminished proliferative responses to all stimulants tested. Treatment with praziquantel did not alter significantly proliferative responses to SEA and SWAP within one month of cure. However responses to all antigens increased significantly at four months post treatment (P<0.05; Bonferroni multiple comparison test). IL-4 and IL-10 levels to all antigens tested increased slightly following treatment. This increase was significant for PHA (Dunn's multiple comparison test) but not for SEA or SWAP. In contrast, IFN- levels to SEA, SWAP and PHA decreased following treatment though insignificantly. HIV co-infection significantly impaired IL-4 and IL-10 responses to PHA but not to SEA or SWAP. However IFN- levels were highest in the HIV seropositive groups (P<0.05; Kruskal-Wallis). IL-4 and IL-10 levels were positively correlated while both cytokines were negatively correlated to IFN- levels confirming the counteregulatory mechanism of Th 1 and Th2 cytokines. The levels of lumphproliferative and cytokine levels were found to be related to CD4 T cell counts (r>0.5, P<0.005; Spearman). These results suggest that HIV does affect immune responses in patients with schistosomiasis. In view of the increasing prevalence of HIV infection as well as the continued spread of schistosomiasis, studies on the consequences of schistosomiasis and HIV co-infection warrant further attention.
- MST-Zoological Sciences