T6 positive cells in the peripheral blood of burn patients: are they Langerhans cells precursors?

ABSTRACT

Peripheral blood mononuclear cells of 14 patients suffering thermal injury were separated by affinity chromatography on peanut agglutinin (PNA) coupled to Sepharose macrobeads. The resulting PNA positive subset was 14% of the total mononuclear population. About 30% of these cells were found to coexpress T6(CD1), Ia-like and the myeloid differentiation antigens My4(CDw14) and Mo1(CD11). In comparison, the PNA+ subset from normal blood donors (about 5% of total mononuclear cells) contained mature monocytes that were found to be T6 negative. Electron microscopic studies using immunogold labeling showed that the T6 positive cells were slightly smaller than monocytes but larger than the classical lymphocytes and had common morphologic features with the Langerhans cells of the skin. Considering that patients suffering extensive damage of the epidermis require fast renewal of all skin elements, it is possible that the cells we identified in their peripheral blood are the precursors of the Langerhans cells of the skin en route from bone marrow to the epidermis.