Immunostimulatory factor(s) in the porcine uterine fluids.

The effects of porcine uterine fluid filtrate (PUF) on lymphocyte activity were examined. PUF was added to porcine lymphocyte cultures in the presence or absence of phytohemagglutinin (PHA), concanavalin A (Con A), or pokeweed mitogen (PWM). Lymphocyte response was determined by 3H-thymidine incorporation. Results indicated that PUF enhanced PHA-, Con A-, and PWM-induced lymphocyte mitogenesis by 222%, 207%, and 261%, respectively, as compared to control. The stimulatory effect of PUF was unlikely to be due to the presence of interleukin-2 in PUF, by evidence that PUF alone did not support cytotoxic T-lymphocyte proliferation, nor was the stimulatory effect due to microbial contamination, because treatment of PUF through PyroBind columns to remove endotoxin did not affect its activity. Incubation of PUF at 56C for 40 min did not alter the enhancement effect. Treatment of PUF with trypsin or pronase for up to 24 hr did not change its activity. In mixed lymphocytes reaction, PUF augmented 3H-thymidine uptake by 242%. The molecular (mol) mass of the immunostimulatory activity in PUF was examined by size-exclusion HPLC, Sephadex G-50, and G-15 gel filtration, and it was found to be 0.8 kDa and < 0.5 kDa. Extracts of porcine endometrium also enhanced PHA-induced lymphocyte mitogenesis, suggesting that the factor(s) may be of uterine origin. In conclusion, we have identified an factor(s) in PUF capable of stimulating lymphocyte mitogenesis and mixed lymphocyte reaction.