The morphology of human (see text for description) DC. (A) Fresh “lineage negative” blood DC, isolated without a period of tissue culture, using immunoselection.57 (May-Grünwald-Giemsa [MGG], original magnification [OM] × 1,433). (B) CMRF-44 sorted, Nycodenz gradient purified cultured blood DC⁷⁷ MGG, OM × 1,433). (C) Tonsil low-density cultured DC stained with anti–HLA-DR. The veils and dendritic processes are more obvious in these preparations (OM × 1,433). (D) Mo-derived DC preparation stained with CMRF-44 using an immunoenzyme (brown, Peroxidase-DAB) technique (in preparation) (OM × 1,433). (E and F ) Fresh “lineage negative” blood DC clustered with CD4⁺ purified autologous T lymphocytes in the presence of staphylococcal entertoxin A (SEA) and MGG stained. The DC is stained in another cluster (F ) for the costimulator molecule CD86 using an immunoenzyme (Alkaline Phosphatase-Fast Blue) technique (OM × 1,197). (G) EM appearances of a CMRF-44–positive cultured blood DC. Note the mitochondria endosomes and lysosomal vacuoles (OM × 17,000). (H) DC in the interstitial tissues of rat heart identified by anti-MHC class II staining (immunofluorescence) (OM × 479). (I) Dermal CMRF-44⁺ DC (red, Peroxidase-AEC) and T lymphocytes (blue, Alkaline Phosphatase-Fast Blue) within a section of normal skin adjacent to a hair follicle (OM × 479). (J) Lymph node interfollicular (T lymphocyte) area containing CMRF-44⁺ IDC (brown, Peroxidase-DAB) compared with CD14 Mo and CD20 B lymphocytes (blue, Alkaline phosphatase-Fast Blue) (OM × 143). (K) Lymph node interfollicular region with CMRF-44⁺ IDC (blue, Alkaline phosphatase-Fast Blue) showing nuclear labeling for the transcription factor Rel B (brown, Peroxidase-DAB) (OM × 1,197). Bar = 10 μm.