SURFACE-MEMBRANE ALTERATIONS IN GUINEA-PIG BASOPHILS UNDERGOING ANAPHYLACTIC DE-GRANULATION - A SCANNING ELECTRON-MICROSCOPIC STUDY

  • 1 January 1981
    • journal article
    • research article
    • Vol. 45  (1) , 58-66
Abstract
Purified guinea pig blood basophils in short-term tissue culture were studied by scanning and transmission electron microscopy, and by 1-.mu.m light microscopic Epon sections after exposure to specific antigen (sheep serum), to guinea pig serum, or to serum-free medium at intervals from 1 min-48 h. Basophils fixed before culture, or after culture in serum-free medium, were spherical cells with uniformly distributed microvilli, ridges and folds. In cultures with guinea pig serum, basophils frequently assumed a hand mirror configuration, characteristic of motile cells, with a single posterior, microvilli-bearing uropod and anterior ruffles. Specific antigen induced basophils to become rounded regardless of the culture medium, and resulted in basophil degranulation and histamine release within 5-20 min. Exposure of cytoplasmic granules to the external medium was initiated by the development, early in degranulation, of a single, 1-2 .mu.m in diameter, opening (degranulation pore) in the plasma membrane. The degranulation pore enlarged progressively over 24-36 h, ultimately permitting the egress of membrane-free cytoplasmic granules. The cell pole opposite the degranulation orifice bore numerous prominent folds and ruffles, changes that persisted for at least 24 h. By 48 h after exposure to specific antigen (sheep serum) the surface features of basophils had reverted to those exhibited by unstimulated control cells.

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