Aa. Zalata et al., WHITE BLOOD-CELLS CAUSE OXIDATIVE DAMAGE TO THE FATTY-ACID COMPOSITION OF PHOSPHOLIPIDS OF HUMAN SPERMATOZOA, International journal of andrology, 21(3), 1998, pp. 154-162
The lipid composition of the sperm membrane has been shown to exert a
significant effect upon the functional quality of spermatozoa. We have
studied the effect of induced peroxidation and of the presence of pol
ymorphonuclear white blood cells (WBCs) on the fatty acid composition
of the phospholipids of human spermatozoa. The spermatozoa were fracti
onated by a discontinuous Percoll gradient in two fractions (47% and 9
0% Percoll). Induced peroxidation of spermatozoa was assessed by deter
mining the production of thiobarbituric acid reactive substances (TBAR
S), mostly malondialdehyde, after incubation with ferrous sulphate and
sodium ascorbate as a promoter of peroxidation. TEARS production afte
r induction of peroxidation was correlated with the abundance of polyu
nsaturated fatty acids (PUFA) (r = 0.68, p < 0.0001), with the double
bond index (r = 0.72, p < 0.0001), and with the oxidative potential in
dex (r = 0.73, p < 0.0001) of fatty acids of phospholipids. In compari
son with samples containing > 1 x 10(6) WBCs/mL, those with < 1 x 10(6
) WBCs/mL contained higher proportions of PUFA (90% Percoll, p < 0.05;
47% Percoll, p < 0.05), total omega 3 fatty acids (90% Percoll, p < 0
.05; 47% Percoll, p < 0.001), docosahexaenoic acid (90% Percoll p < 0.
05, 47% Percoll, p < 0.05), and double bond index (90% Percoll, p < 0.
05; 47% Percoll, p < 0.001). In addition, mean melting point was signi
ficantly lower (90% Percoll, p < 0.05; 47% Percoll, p < 0.001) in samp
les with < 1 x 10(6) WBCs, indicating higher membrane fluidity. The in
crease of TBARS production by spermatozoa after incubation with the xa
nthine-xanthine oxidase system and/or ferrous sulphate as promoter of
peroxidation was associated with a significant decrease of PUFA. Incub
ation of spermatozoa with WBCs, with or without activation by phorbol
eater, decreased the PUFA (p < 0.05). Also, TEARS production was incre
ased (p < 0.01) after activation of WBCs with phorbol ester. Our data
provide evidence that oxidative stress induced by WBCs has a damaging
effect on the polyunsaturated fatty acids of sperm phospholipids which
may result, amongst other effects, in decreased membrane fluidity.