“…The most extensively studied APC include macrophages, B cells and lymphoid dendritic cells, all of which are capable of endocytosis of foreign antigens, processing of these proteins into small peptides, and presentation of peptide-Class II MHC complexes to T cells. In the course of recent studies (2) evaluating the eflScacy of various APC in presenting antigens of West Nile Virus (WNV) to polyclonal populations of murine, CD4+, WNV-specific T cells it became evident that high APC numbers pulsed with high WNV antigen concentrations suppressed T cell proliferation. These observations were reminiscent of those of Lamb et al Abbreviations used in this paper: APC, antigen-presenting cell(s); B14, B cells derived from 14 day West Nile virus-primed mice; Bo, B cells derived from naive mice; B++++, B cells derived from the mice hyperimmunized with West Nile virus; DC, dendritic cells; DMEM, Dulbecco's modified Eagle's medium; EMEM, Eagle's minimal essential medium; FcR, Receptors for immunoglobulin Fc piece; FCS, fetal calf serum; hkLM, heat-killed Listeria; i.v., intravenous; LM-induced, Listeria-induced; ME, 2-mercaptoethanol; MHC, major histocompatibility complex; NMS, normal mouse serum; PEC, peritoneal exudate cells; p.f.u., plaque forming units; PG, prostaglandins; S : R ratio, stimulator to responder ratio; TcR, T cell receptor; TH-induced, thioglycollate-induced; WNV, West Nile virus.…”