OBJECTIVETo study the effect of rhTNF-alpha on human sperm mitochondrial function and motility in vitro.

METHODSFifty-six semen samples collected by masturbation were analyzed according to WHO protocols. Semen samples from 40 healthy men were prepared using Percoll centrifugation. Sperm suspension was diluted to a concentration of 10 x 10(6)/ml in Ham's F10 medium. Sperm samples were incubated with rhTNF-alpha solution (final concentration 0.03 microg/L, 0.06 microg/L, 0.09 microg/L and 0.27 microg/L, respectively) for 0.5 h, 1 h, 2 h, 3 h and 4 h at 37 degrees C in 5% CO2, and comparative studies were made with a control group. Ten microl sperm samples were examined with CASA technique, 250 microl stained in the presence of 10 microg/ml Rh123 and PI, and mitochondrial function analyzed by flow cytometry.

RESULTSSignificant differences were found between the experimental groups (final concentration 0.06 microg/L, 0.09 microg/L and 0.27 microg/L) and the control group in viability, straight line velocity, curvilinear velocity, average path velocity, progressive motility of human sperm and the number of spermatozoa with normal mitochondrial function (P < 0.01) except the final concentration 0.03 microg/L group (P > 0.05). Motility of human sperm lowered with the increase of rhTNF-alpha concentration and incubation time, and r values were 0.675, 0.691, 0.762, 0.693, 0.724 and 0.571, 0.594, 0.752, 0.791, 0.816, respectively (P < 0.01). The number of spermatozoa with normal mitochondrial function decreased with the increased rhTNF-alpha concentration and incubation time, and r values were 0.615, 0.643, 0.752, 0.691, 0.754 and 0.532, 0.567, 0.782, 0.692, 0.854, respectively (P < 0.01).

CONCLUSIONrhTNF-alpha can reduce human sperm motility function in vitro, possibly by interfering with human sperm mitochondrial function.