Human lymphocyte responses to Plasmodium falciparum merozoite antigens. A functional assay of protective immunity?

Merozoites obtained from cutaneous cultures of Plasmodium falciparum were used as antigen for an in vitro lymphocyte assay. Antigen specific proliferative responses were observed with lymphocytes from individuals with long-standing immunity to P. falciparum. Donors whose last P. falciparum challenge occurred within the year preceding the assay exhibited lymphocyte responses significantly higher than those from donors whose infection was more remote. This suggests that a lymphocyte dependent assay may relate to the protective status of the donor.