It has been postulated that seminal plasma contains a potent immunosuppressive factor(s) which play a critical role h preventing sensitization of females to sperm antigens after insemination. It has been shown that human seminal plasma (HuSePl) inhibited phytohemagglutinin(PHA) and Concanavalin A(ConA) induced blast transformation of normal peripheral blood lymphocytes.
To analyze protein fractions of HuSePl and to observe suppression of cell-mediated immune response by each fraction, the authors performed the Sephadex G-100 chromatography and the lymphocyte transformation with parameters of purified PHA(PHA-P) and pokeweed mitogen(PWM) stimulation test.
The results were as follows;
1. Sephadex G-100 chromatography of HuSePl yielded five fractions(Fr. 1-5).
2. The molecular weight of each fraction, assessed by sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS.PAGE), was from 14,000 daltons(D) to more than 85,000 D in Fr. 1, 42,000 D and 33,000 D in Fr. 2, 43,000 D in Fr. 3, 20,000 D in Fr. 4 and 19,000 D in Fr. 5.
3. The mean percentages .of suppression in PHA-P stimulation test by fractions isolated from HuSePl in male (n=I3) were 59.8+10.1% in Fr. 1, 59.5+23.0% in Fr. 2, 84.2+9.4% in Fr. 3, 60.9+- 2l.4% in Fr. 4, 49.4+-23.2% in Fr. S(F=6.=8, P <0.01) and in female (n=13) were 64.6+- 11.7 % in Fr. 1, 65.4+13.1% in Fr. 2, 82.9+9.2% in Fr. 3, .55.4+21.5% in Fr. 4, 59.2+-26.0% in Fr. 5(F=4.76, P <0.01).
4. The mean percentages of suppression in PWM stimulation test by fractions isolated from HuSePl in male (n=11) were 15.8+-17.1% in Fr. 1, 45.1+18.6% in Fr. 2, 80.4+2.7% in Fr. 3, 61.7 + 4.2 % in Fr. 4, 63.5+- 12.8% in Fr. 5(F=38.91, P<0.01) and in female (n=11) were 9.5+- 15.3% in Fr. 1,32.9+- 20.5% in Fr. 2, 78.7+4.5% in Fr. 3,59.9+- 10.0% in Fr. 4, 55.3+15.2% in Fr. 5(F =39.65, P <0.01).
5. The sex difference was not significant in PHA and PWM stimulation test with each fraction (P>0.05). The results revealed that the Fr. 3 has the strongest suppressive effect on lymphocyte transformation activity and these observations support the concept that a local immune response against sperm in the female reproductive tract is actively suppressed by a component in seminal plasma.
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