Summary
Four methods of platelet lysis, namely, sonication, nitrogen cavitation in a high
pressure bomb, the use of a “no clearance” tissue homogenizer and simple osmotic lysis
have been compared in terms of ease, effectiveness and reproducibility in comparison
with a method involving the hypotonic lysis of glycerol-loaded platelets ; the most
extensive studies have been carried out using sonication and the tissue homogenizer.
In order to reduce the degree of fragmentation of the platelet membrane, the use of
surface stabilizing agents such as zinc chloride and fluorescein mercuric acetate
have also been investigated. Membranes obtained in these different ways have been
isolated by centrifugation on continuous or discontinuous sucrose density gradients
and the resulting fractions compared by electron microscopy, enzymatic activity, chemical
analysis and hemagglutination inhibition. The glycerol-lysis technique was found to
be most effective (85%) in untreated platelets and the degree of lysis was considerably
reduced in platelets hardened by the zinc chloride method. Ultrastructural studies
showed that the largest membrane fragments (175 nm) were obtained by glycerol lysis
of untreated platelets and that smaller vesicles (50-100 nm) were obtained by the
other techniques even following membrane stabilization. Double membrane structures
were obtained in several of these methods.
