GnRH agonist induces suppression of lymphocyte subpopulations in secondary lymphoid tissues of prepubertal female mice.

Problem: Gonadotropin-releasing hormone (GnRH) agonists are playing an increasing role in the medical management of a variety of diseases. Recent evidence also indicates GnRH immune system interactions.

Method: The present study investigated the sequential changes in lymphocyte subpopulations in secondary lymphoid tissues of prepubertal female mice in vivo following Lupron depot administration. A direct two-color immunofluorescence staining followed by flow cytometric analysis was employed.

Results: Following agonist administration, white blood cell counts decreased significantly with decreases in both granulocyte and lymphocyte counts. Blood T-cell and B-cell subsets were also reduced although B cells decreased more markedly. In the spleen, B cells were again reduced more than T cells. There was no selective loss of either CD4 or CD8 subpopulations at any time point, in both spleen and blood. There were no differences in the percentage of lymph node subsets except that B cells decreased in the second week.

Conclusions: These data indicate that GnRH agonist alters specific lymphocyte subpopulations and, therefore, have the potential for affecting immune system function in vivo.