Objective: To study the effects of prolactin on interactions between Graves' disease (GD) thyrocytes and autologous peripheral blood mononuclear cells (PBMC) in coculture.
Methods: Primary thyrocytes and autologous PBMC were cocultured at various levels of ovine prolactin (oPRL) in vitro. The activation and proliferation of PBMC as well as HLA-DR and CD(40) expressions on thyrocytes were determined by immunofluorescent staining and flow cytometry.
Results: With PBMC in GD cocultures, oPRL caused significant increase in the percentage of CD(4)(+) CD(25)(+) cells at 200 microg/L [(13.08 +/- 2.54)%, P < 0.01] and in the proliferative index at 200 microg/L [(17.82 +/- 3.02)%, P < 0.01] and 1,000 microg/L [(16.57 +/- 2.56)%, P < 0.05], but not at 12.5 microg/L [(10.43 +/- 2.38)% and (14.08 +/- 2.67)%, respectively] or 50 microg/L [(9.94 +/- 2.54)% and (14.56 +/- 2.80)%, respectively)]. The values at 200 or 1,000 microg/L as above were also significantly different from those at 12.5 or 50 microg/L. The percentage of CD(40)(+) cells [(48.25 +/- 6.63)%, (52.28 +/- 6.94)%] and delta mean fluorescence intensity (dMF; 42.94 +/- 10.24, 49.51 +/- 12.34) were significantly lower in thyrocytes in GD cocultures treated with 200 or 1,000 microg/L oPRL than those untreated [(58.38 +/- 6.62)% and 67.30 +/- 20.20] or treated with two other concentrations of oPRL. The percentage of HLA-DR + cells [(46.79 +/- 7.51)%, P < 0.01] and dMF (21.02 +/- 5.43, P < 0.01) were significantly higher in the thyrocytes treated with 50 microg/L oPRL than those untreated [(33.51 +/- 8.58)% and 13.91 +/- 3.88] or treated with three other concentrations. There were no significant differences between the dose groups of oPRL but those mentioned above.
Conclusions: Prolactin could affect interactions between GD PBMC and autologous thyrocytes and might eventually influence the shift of helper T cells. High prolactin levels might aggravate GD.