Cell type specificity and developmental expression of the L2/HNK-1 epitopes in mouse cerebellum.

The developmental expression of carbohydrate epitopes recognized by monoclonal antibodies HNK-1 and L2 was studied in tissue sections and cultures of mouse cerebellum. At all ages studied the 2 antibodies had identical staining patterns. In cultures of embryonic and early postnatal mice some, but not all cells of all 3 major neural cell types, neurons, astrocytes and oligodendrocytes, but not fibronectin-positive fibroblast-like cells were labeled by the antibodies. The most intensely labeled cells were those with antigenic marker profiles characteristic of immature glia. L2/HNK-1 epitope expression on neuron precursors was detected most convincingly in sections, where the band of migrating granule cell precursors in the external granular layer of the embryo and outer part of the external granular layer at early postnatal ages were strongly labeled by the antibodies. In sections of adult cerebella an overall reduced, but detectable level of L2/HNK-1 epitope expression was seen in all layers, but slightly more prominently in granular layer and white matter. At embryonic ages ventricular cells did not express detectable levels of epitopes. Most of the present data support the notion that the L2/HNK-1 epitopes are most strongly expressed on cell types with properties of glial and neuronal precursor cells.