alpha-1-antichymotrypsin: interaction with chymotrypsin-like proteinases
The interaction of human plasma alpha-1-antichymotrypsin with serine proteinases from different tissues has been investigated. The protein was found to form stable complexes with pancreatic chymotrypsin, leukocyte cathepsin G, and mast cell chymotrypsin. No inhibition of pancreatic trypsin or leukocyte elastase could be demonstrated. With mixtures containing both alpha-1-antichymotrypsin and alpha-1-proteinase inhibitor, it was found that the former preferentially inactivated leukocyte cathepsin G, while the latter showed a strong preference for pancreatic chymotrypsin.
However, leukocyte elastase was specifically inactivated by alpha-1-proteinase inhibitor even in 1:1 mixtures with chymotrypsin. All of these results taken together suggest that one of the primary functions of alpha-1-antichymotrypsin is to inactivate leukocyte cathepsin G, while alpha-1-proteinase inhibitor controls the activity of other serine proteinases, particularly leukocyte elastase.
CYTOMORPHOLOGY OF SOLID-PSEUDOPAPILLARY NEOPLASM:
- • highly cellular aspirate
- • myxoid or hyalinized vascular stalks lined by neoplastic cells
- • delicate granular cytoplasm, indistinct cell borders
- • round or oval nuclei
- • nuclear grooves
- • inconspicuous nucleoli
- • foam cells, necrotic debris
FNA yields highly cellular smears composed of a monotonous population of cuboidal cells arranged in loosely cohesive groups, as isolated cells, and, most characteristically, as a single or multiple layer around vascular structures that are often thickened by a myxoid or hyaline material (Fig. 13-7A). The tumor cells have delicate granular cytoplasm with indistinct cell borders. The nuclei are round to oval with finely dispersed chromatin, smooth or grooved nuclear contours, and indistinct nucleoli (Fig. 13-7B). Mitotic figures are usually inconspicuous. The background may contain abundant blood, foam cells, globules of amorphous myxoid material, and necrotic debris.
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