[Effects of prolactin on in-vitro interactions between thyrocytes from patients with Graves' disease and autologous peripheral blood mononuclear cells].

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.