Acute Chagas' disease: plasma levels of alpha-2-macroglobulin and C-reactive protein in children under 13 years in a high endemic area of Bolivia.

We measured the levels of two human acute phase proteins (APP), alpha-2-macroglobulin (A2M) and C-reactive protein (CRP), in sera of 56 healthy and 84 acute chagasic children aged from 1 to 13 years old, from a highly endemic area in Bolivia. In such areas, children are continuously exposed to vectors and the frequency of acute cases increases with age. Quantitation of A2M and CRP were performed using sandwich ELISAs, that were shown to be sensitive, reproducible and suited for studying many samples rapidly. A2M levels observed were higher in healthy younger children, decreasing with age until children reached their teens, and their distribution suggested a relationship between A2M concentration and age that could be consistently expressed by a power function. The same does not occur with CRP levels. Concentrations of A2M were age-adjusted to allow comparison using sera collected from children with different ages. Both A2M and CRP were significantly increased in acute chagasic children. Since parasites are commonly present in blood and tissues during the acute phase of Chagas' disease, it is possible that the high levels of A2M may act as inhibitors of a high load of proteinases, derived either from the parasites, from host cell damage or from both.