The mast cells of the mammalian central nervous system. IV. Culture of neurolipomastocytoid cells from rabbit and rat leptomeninges.

Leptomeningeal cells of 1-3 day-old rabbits and rats were cultured in Hamm's complete medium or in Eagle's Basal Medium (BME); the latter proved to be favorable for the present research. Three types of granular cell could be differentiated and isolated from other mesenchymal, neuronal and neuroglial elements. These three closely resembled (i) mast cells (MCs), (ii) neurolipomastocytoid cells (NLMs), and (iii) typical macrophages. Because MCs are absent from adult rabbit leptomeninges but present in the rat, it was concluded that the MC-like elements in rabbit cultures were derived from precursor cells normally capable of producing NLMs. The macrophages appeared typical, but their cell of origin, as that of the MCs and NLMs, could not be determined conclusively; a small round mononuclear cell might have given rise to all three cell types. NLMS, like MCs but unlike macrophages, are sensitive to the MC-discharger compound 48/80. This finding, plus the peculiar morphological features of the NLMs, in addition to evidence of a strong phagocytic activity by the macrophages, distinguishes the mature NLMs from mature macrophages as distinct cellular entities. It is closely concluded that NLMs in culture resemble ordinary MCs more closely.