Seminal leukocytes are Good Samaritans for spermatozoa.

OBJECTIVE: To assess the effect of leukocytospermia on assisted reproductive technology outcomes.
DESIGN: Retrospective analysis.
SETTING: University laboratory. PATIENT(S): Couples attending the infertiliy clinic and involved in ART program for IVF or ICSI. INTERVENTION(S): During a 7-year follow-up in an assisted reproductive technology program, leukocytospermia was routinely determined using the peroxidase technique. Donor sperm were excluded from the study. MAIN OUTCOME MEASURE(S): Egg retrievals (N = 3,508) were distributed in 3 groups according to the leukocyte levels in semen from which fertilizing sperm were extracted: group 1, absence of leukocytes (n = 3,026); group 2, moderate leukocytospermia (<10(6)/mL) (n = 344); or group 3, high leukocytospermia (≥10(6)/mL) (n = 138). They resulted in 1,463 IVF and 2,045 intracytoplasmic sperm injection procedures that gave 802 clinical pregnancies. RESULT(S): Surprisingly, the fertilization rate, cleavage rate, clinical pregnancy rate, gestational age, and mean infant weight were significantly improved when seminal leukocytes were present, regardless of the technique used. The only negative side effects associated with a high level of seminal leukocytes (group 3) were an elevated rate of early pregnancy loss (from 26.6% to 40.5%) and a 3-fold increase in the percentage of ectopic pregnancies. CONCLUSION(S): At moderate levels (<10(6)/mL), leukocytospermia appears to be physiologic. It is associated with improved sperm fertilization ability and pregnancy outcome. At higher concentrations, leukocytospermia alters neither sperm fertilization ability nor the probability of clinical pregnancy when compared with nonleukocytic patients with infertility. However, the pregnancy outcome is reduced.