Tissue culture studies of neurofibromatosis: Effects of axolemmal fragments and cyclic adenosine 3′,5′‐monophosphate analogues on proliferation of schwann‐like and fibroblast‐like neurofibroma cells

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Abstract
Six dermal neurofibromas obtained from 5 patients with neurofibromatosis were dissociated and the cells were plated on polylysine‐coated glass. Two principal cell types were observed in the cultures: elongated and bipolar Schwann‐like cells (SLCs), and polymorphic flattened fibroblast‐like cells (FLCs). Indirect immunofluorescence demonstrated that SLCs expressed surface laminin but not surface fibronectin; FLCs expressed surface fibronectin but were only weakly positive for surface laminin. Tritiated thymidine autoradiography demonstrated that cultured SLCs proliferated slowly (labeling index, 0.7 to 4.0%), whereas FLCs divided more rapidl%(labeling index, 7.5 to 26.4%). Axolemmal fragments prepared from human or rat central nervous system specimens adhered to SLCs derived from each of the 6 neurofibromas, but not to FLCs. Axolemmal fragments induced a marked proliferative response of SLCs from 2 of the 6 neurofibromas but had no effect on proliferation of SLCs from the other 4 neurofibromas or FLCs from any of the 6 neurofibromas. In one patient from whom 2 neurofibromas were obtained, SLCs from one neurofibroma responded to axolemmal fragments, while SLCs from the other did not. Treatment of the cultures with 0.1 mM cyclic adenosine 3′,5′‐monophosphate (cAMP) analogue, 8‐bromo cAMP, caused marked inhibition of proliferation of both SLCs and FLCs derived from all 6 neurofibromas. The same concentration of another cAMP analogue, dibutyryl cAMP, inhibited proliferation of SLCs but not of FLCs.