LCH cells from eosinophilic granuloma are immature DCs but may be induced to express membrane class II and C86 and to stimulate allogenous lymphocytes on stimulation with CD40L.

(A) Sections from bone lesion of patient 10337 (eosinophilic granuloma), lymph node from patient 6277 (multisystem disease), and skin from patient 4968 (cutaneous histiocytosis) were stained with antibody to CD40. (B) Control immature (□) and mature (■) (CD40L treated) monocyte-derived DCs and CD1a⁺ (●) and CD1a⁻ (○) cells sorted from fresh eosinophilic granuloma tissue from patient 7459 were cultured with 10⁵ allogenous lymphocytes at 1% or 4% stimulator to effector ratio. (C) sorted CD1a⁺ cells from eosinophilic granuloma from patient 10391 (▴, ⧫) and control monocyte-derived DC (□, ■) were either cultured with LcCD32 (▴, □) or with LcCD40L (⧫, ■) for 2 days, and then cultured with 10⁵ allogenous lymphocytes at 1% or 4% stimulator to effector ratio. Note that LCH CD1a⁺cells, either fresh or cultured with LcCD32 stimulate T-cell proliferation in a similar manner to that of control immature monocyte-derived DCs, whereas LCH CD1a⁺ cells cultured with LcCD40L stimulate T-cell proliferation in a similar manner to that of control mature monocyte-derived DCs cultured with LcCD40L. (D) The same experiment was performed with fresh tissue from eosinophilic granuloma from patient 3774. (E) Sorted CD1a⁺ cells from eosinophilic granuloma from patient 10391 cultured with LcCD32 or with LcCD40L for 2 days were also analyzed by confocal microscopy for expression of HLA-DR (green) and CD86 (red). Note that green DR staining increased and is present at the cell surface, in cells cultured with LcCD40L, and that red CD86 staining, absent on cells cultured with LcCD32, is induced on cells cultured with LcCD40L.