RESUMO
Antibody F(ab')2 fragments derived from the sera of four patients with histology-proven chronic Chagas myocarditis [cF(ab')2]-complexed antibody F(ab')2 fragments of children with acute Trypanosoma cruzi infection [aF(ab')2] in significantly higher molar ratios than those measured with F(ab')2 antibody fragments of normal subjects [nF(ab')2] from nonendemic areas (p less than 0.05). Anti-idiotype [cF(ab')2 X aF(ab')2] immune-complex formation was significantly blunted by preabsorption of cF(ab')2 with porcine heart atria sarcolemma (PAMs) immobilized on sepharose beads (inhibition, mean, 78.1 +/- 2.4%, n = 4). cF(ab')2 X nF(ab')2] immune-complex formation was also inhibited by pretreatment of cF(ab')2 with PAMs (inhibition, mean, 48.7 +/- 7.5%, n = 4). The sera of three groups of subjects from a geographic zone endemic for T. cruzi infection in the northeast of Brazil were assayed for free and immune-complexed IgG anti-acute T. cruzi infection F(ab')2. The indexed levels of free IgG anti-idiotype antibody activity and levels of IgG anti-idiotype immune complexes (IC') were markedly elevated in hospitalized patients with severe, decompensated chronic Chagas myocarditis (n = 23), and their IC' indexes were significantly higher than those measured in asymptomatic seropositive subjects from a nearby endemic village of the northeast of Brazil (Moniz Ferreira, n = 92, p less than 0.001) and in healthy seronegative villagers (n = 84, p less than 0.001). There exists a strong correlation between elevated IgG anti-sarcolemma, anti-idiotype activity levels and the clinical and pathologic expression of chronic Chagas myocarditis.