Wortmannin, an inhibitor of phospholipase D activation, selectively blocks major histocompatibility complex class II-restricted antigen presentation.
Wortmannin, a fungal metabolite, is a specific inhibitor of phospholipase D (PLD) activation. Presentation of defined exogenous soluble proteins to specific T cell hybridomas was studied by using different antigen-presenting cells (APC): IA-positive peritoneal macrophages (M phi), B lymphoma cells (B) or dendritic cells (DC). Major histocompatibility complex class II-restricted antigen presentation by M phi was blocked when cells were pretreated with wortmannin. However, when cells constitutively expressing IA molecules (B, DC) were used as APC, no inhibition was observed. Additionally, MHC class I antigen presentation was not impaired by wortmannin. Moreover, wortmannin does not block either peptide presentation or presentation to autoreactive T cells. This effect was time and dose dependent and occurred at the level of intracellular handling of the antigen. Mainly because it was not a toxic inhibition, it was reversible with time and neither antigen uptake and catabolism, nor IA synthesis were affected. Because M phi, but not B or DC, express PLD activity and only the former were blocked by wortmannin in antigen presentation, our results strongly suggest that a differential antigen-processing pathway exists in these disparate APC, which could be based essentially on a wortmannin-sensitive, PLD-dependent step present in M phi but absent and/or unnecessary in both B lymphoma cells and DC.
Carrasco-Marín
E
E
Servicio de Inmunología, Hospital Universitario Marqués de Valdecilla, Santander, Spain.
Alvarez-Domínguez
C
C
Leyva-Cobián
F
F
D000730:Androstadienes / Q000494:pharmacology*; D000818:Animals; D017951:Antigen Presentation / Q000187:drug effects*; D000938:Antigen-Presenting Cells / Q000187:drug effects / Q000201:enzymology*; D001402:B-Lymphocytes / Q000201:enzymology; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000201:enzymology; D005260:Female; D015395:Histocompatibility Antigens Class I / Q000235:genetics; D000949:Histocompatibility Antigens Class II / Q000235:genetics; D006825:Hybridomas / Q000276:immunology; D008264:Macrophages / Q000201:enzymology* / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000502:physiology*; D013601:T-Lymphocytes / Q000276:immunology; D000077191:Wortmannin
D000730:Androstadienes; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D010739:Phospholipase D; D000077191:Wortmannin