Analysis of CD1 molecules on haematological malignancies of myeloid and lymphoid origin. II. Intracellular detection of CD1 antigens.

The surface and cytoplasmic expression of CD1a molecules was analysed by indirect immunofluorescence (IIF) and dot blot assay (DBA) in a panel of 40 acute and chronic leukaemias. Thirty-two per cent of the samples were positive by IIF but, surprisingly, 72 per cent of the patients were positive by DBA, suggesting the intracellular presence of these molecules, CD1b and CD1c were also detected by DBA at similar percentages. Immunocytochemical staining of cytocentrifuge preparations confirmed the intracellular presence of CD1a, CD1b, and CD1c in leukaemic cells of pre-B, B, T, and non-lymphoid lineages.