Potent immunostimulatory dendritic cells can be cultured in bulk from progenitors in normal infant and adult myasthenic human thymus.

Low density cells can readily be enriched from thymus tissue both of children undergoing cardiac surgery and of older patients with myasthenia gravis, and can be cryostored in bulk. When fresh or thawed cells are cultured with granulocyte-macrophage colony-stimulating factor and stem cell factor with or without tumour necrosis factor-alpha (TNF-alpha), they generate numerous cells with the characteristic ultrastructural, phenotypic and functional properties of dendritic cells. These proved to be very potent, both as stimulators of primary mixed leucocyte responses and as costimulators in oxidative mitogenesis. Especially after exposure to TNF-alpha, these dendritic cells also processed a natural epitope from a 437-residue polypeptide and presented it efficiently to an autoimmune T-cell clone (of T helper type 0 phenotype). Thus, immunostimulatory dendritic cells can be cultured in relative abundance from progenitors in infant and adult human thymus. Both are convenient sources of potent antigen-presenting cells of identifiable origins, e.g. for use in selecting human T-cell lines.