In situ characterization of the human hyalocyte
H. S. Lazarus and G. S. Hageman
Wilmer Ophthalmological Institute, Johns Hopkins Hospital, Baltimore, Md.
OBJECTIVE: To provide more definitive evidence regarding the cellular
origin of hyalocytes and to establish a basis for their identification in
tissue specimens. METHODS: Hyalocytes were examined in situ in human eyes
from 10 donors (aged 1 to 63 years) with use of a panel of antibodies and
lectins directed against determinants associated with leukocytic and
nonleukocytic cells. RESULTS: Hyalocytes express the leukocyte-associated
antigens CD45, CD11a, and CD64, an antigen expressed constitutively only by
monocytes and macrophages. However, they do not react with antibodies
against CD68, an antigen that is expressed by virtually all tissue
macrophages, or CD 11b and CD 14, antigens that are variably expressed by
the monocyte/macrophage lineage. They also react with antibodies against
major histocompatibility complex class II antigens and S100, both of which
are expressed by a variety of cell types. The lectins Dolichos biflorus,
Sambucus nigra, Griffonia simplicifolia, Limax flavus, and Ricinus communis
I bind hyalocyte-associated glycoconjugates; no binding was observed with
Arachis hypogaea or Glycine max. CONCLUSIONS: These results provide strong
evidence that hyalocytes belong to the monocyte/macrophage lineage but
differ significantly from other tissue macrophages in that they express
S100 protein and do not express CD68. This information should provide a
basis for the identification of hyalocytes in tissue specimens and an
improved understanding of vitreo-retinal pathologic features.
