Decidual immune cell infiltrate in hydatidiform mole

Hydatidiform mole is a gestational trophoblastic disease characterized by proliferation of the pregnancy-associated trophoblastic tissue. Complete hydatidiform mole is an entirely paternally derived lesion, and therefore, represents complete intrauterine allografts that can induce an altered maternal immune response Hypothesis: Here, we hypothesize that "the development of hydatidiform moles is associated with numeric alterations of the decidual immune cell infiltrate."

A total of 30 specimens (decidual tissue), entailing normal first trimester pregnancy terminations and complete hydatidiform moles (15 cases, each), were evaluated for immune cell infiltrate using immunohistological methods and monoclonal antibodies (CD20, CD68, and CD3 for B cells, histiocytes/dendritic cells, and T cells, respectively).

Groups of immune cells were seen in the decidual tissue of first trimester normal pregnancy terminations and hydatidiform moles. Compared to the decidual tissue of first trimester normal pregnancy terminations, the mean counts of the immune cells were statistically significantly higher (p< 0.05) in the decidual tissue of the hydatidiform moles (0.33 +/- 0.21 vs. 1.66 +/- 0.21 for CD20(+)B cells; 9.80 +/- 1.57 vs. 13.14 +/- 1.16 for CD68(+) cells; and 12.92 +/- 3.46 vs. 23.85 +/- 1.22 for CD3(+) cells for decidual tissue without and with molar changes, respectively).

Hydatidiform moles are associated with numeric alterations of immune cell infiltrate. The numeric dominance of immune cells in the hydatidiform moles may reflect either non-specific or specific immunological processes. The possible pathogenetic and prognostic ramifications of our findings are open for further investigations.