Clinical forms of human Schistosoma mansoni infection are associated with differential activation of T-cell subsets and costimulatory molecules

The current study has compared the activation status and the expression of the CD28 molecule on circulating CD4(+) and CD8(+) lymphocytes from patient s with different clinical forms of schistosomiasis. The data show that pati ents with acute schistosomiasis have an increase on the mean percentage of CD4(+)HLA-DR+ cells, whereas chronic asymptomatic patients exhibit an incre ased mean percentage of CD8(+)HLA-DR+ cells. Patients with the hepatospleni c disease showed an increase in both CD4(+)HLA-DR+ and CD8(+)HLA-DR+ cells. Despite the high levels of CD8(+)HLA-DR+ cells in hepatosplenic patients, they presented a decreased ratio of CD8(+)CD28(+)/CD8(+) cells. These findi ngs of a different percentage of circulating CD8(+)CD28(+) cells might expl ain the different in vitro cellular reactivity of asymptomatic and hepatosp lenic patients and the defects in the cytokine secretion patterns reported in individuals with hepatosplenic schistosomiasis.