MHC class I- and class II-restricted processing and presentation of microencapsulated antigens

Macrophages were found of having a strong capacity of phagocytosing small s ize microcapsules (MS) and presentating microencapsulated antigens to eithe r CD4+ and CD8+ T cells, The class I-restricted presentation of microencaps ulated tetanus toroid by macrophages requires an intracellular processing w hich might follow the phagosome-to-cytosol route to enter the classical MHC class I presentation pathway. In contrast, presentation of microencapsulat ed cytotoxic peptide PbCS252-260 to specific CD8+ T cells has been observed with different APC and is not blocked by cytochalasin D, suggesting that p eptide released from MS may directly bind to MHC class I molecules on the c ell surface. In the case of MHC class II-restricted T cells, prefixation or treatment of macrophages with chloroquine, brefeldin A and cycloheximide i nhibits the presentation of microencapsulated and soluble tetanus toroid. T hese findings illustrate the capacity of microencapsulated antigens to ente r different presentation pathways and should facilitate the development of subunit vaccines. (C) 1999 Elsevier Science Ltd. All rights reserved.