Cellular responses to Plasmodium falciparum major surface antigens and their relationship to human activities associated with malaria transmission.

In Brazil, two types of activities have led to the worsening of malarial transmission in the Amazon region: prospecting/mining and agricultural settlements. In the present study, we analyze the cellular response of 52 of these individuals (14 gold-miners and 38 farmers) living within the same endemic area. Two Plasmodium falciparum major surface antigens (recombinant proteins) were used for cellular proliferative assays: circumsporozoite protein and merozoite surface protein-1. The frequency of these cellular responses were significantly higher among the miners (57-64%) than the farmers (10-20%) when either recombinant protein was used. Our data suggest that a higher exposure to malaria of the gold-miners contributed to their higher in vitro cellular response compared with the farmers. These findings point the way to further studies evaluating the influence of risk factors associated with the life styles of different social groups and the immune responses to these antigens.