Phospholipids associated with human parotid gland sialoliths

Ca-acidic phospholipid-phosphate complexes (CPLX) were isolated from 6 whole and 2 pooled human parotid sialoliths containing the mineral phases hydroxyapatite, whitlockite and octacalcium phosphate (ash 78 +/- 16 per cent, n = 7). Total lipids accounted for 25 per cent of the demineralized dry weight of these sialoliths. CPLX was 39 +/- 18 per cent of the lipid phosphorous pool, while diphosphatidyl glycerol, phosphatidyl ethanolamine and phosphatidyl choline were the principal non-complexed phospholipids. The high cholesterol:phospholipid molar ratio (1.0 +/- 0.3) observed in the sialolith lipids suggests a plasma membrane origin for these lipids.