Decreased CD4 and increased CD8 counts with T cell activation is associated with chronic helminth infection

We have previously reported the presence of marked immune dysregulation wit h a dominant Th2 profile, in a population of Ethiopian immigrants (ETH) in Israel heavily infected with helminths. In order to characterize better thi s immune dysregulation we studied by how cytometry the expression of severa l activation markers on peripheral T cell populations, and lymphocyte apopt osis, in blood samples obtained from 63 'new' ETH (recently arrived), 18 'o ld' ETH (>5 years since immigration) and 34 non-Ethiopian Israelis. The mai n findings in the 'new' ETH group in comparison with the non-Ethiopian cont rols were: (i) decreased CD4 and increased CD8 lymphocyte counts; (ii) elev ated levers of activated T cells (CD3, CD4 and CD8) expressing HLA-DR; (iii ) decreased levels of 'naive' CD4(+) cells (CD45RA(+)), with increased leve ls of 'memory' CD4(+) cells (CD45RO(+)); (iv) decreased numbers of CD28(+) CD8(+) lymphocytes; (v) marked increase in lymphocyte apoptosis. These T ce ll alterations and activation profile remained unchanged in IO 'new' ETH in whom the helminth infections persisted for 6-11 months, in contrast, in 18 'old' ETH, without helminth infections, the T cell activation profile was within the normal range. These findings suggest that chronic helminth infec tions may have a profound effect on the immune system of the host that disa ppears after eradication of these infections and adjustment to the new envi ronment. It should therefore be taken into consideration for every immunomo dulation therapy and especially in vaccine design and trials, in regions en demic for helminth infections.