Sensitization in vitro of human peripheral blood mononuclear cells to phenolic glycolipid 1 of Mycobacterium leprae in liposomes

Study of primary immune responses in leprosy has been limited, since disease becomes manifest long after infection or is not detectable. To study primary immune responses, we immunized in vitro human peripheral blood mononuclear cells from unexposed individuals using phenolic glycolipid 1 (PGL-1), an important water-insoluble antigenic constituent of Mycobacterium leprae. PGL-1, encapsulated in liposomes, induced lymphoproliferation or, less frequently, suppression of lymphoproliferation in 11-day lymphocyte cultures. The primary lymphocyte responses resembled those elicited with keyhole limpet hemocyanin (KLH). HLA-DR2 expression, associated with tuberculoid leprosy, did not influence the outcome of in vitro sensitization. The association of HLA-DR2 and tuberculoid leprosy is not explained by differential ability to generate primary lymphoproliferative responses to PGL-1 or KLH. We have extended in vitro sensitization methodology to include a water-insoluble antigen in antigen-bearing liposomes. This methodology is potentially useful for studies of immunogenetics and immunopathology, and for vaccine research.