AJRl1998; zyxwvutsrqponmlk 39:256-265 Printed in the United States of America zyxwvutsrqpon - all rights reserved Copyright zyxw 0 Munksgaard. 1998 ISSN zyxw 8755-8920 Amerlcan zyxw journal of Reproductlve ImmunologU Changes in Lymphoid Tissue After Treatment with zyxw a Gonadotropin Releasing Hormone Antagonist in the Neonatal Marmoset (Calltjhrix jacchus) DAVID R. MA", SARAH HOWIE, DOUGLAS F. PAULSEN, MUKAILA A. AKINBAMI, STEPHEN F. LUNN, AND HAMISH M. FRASER Mann DR, Howie S, Paulsen DF, Akinbami MA, zyxwvutsrq Lunn SF, Fraser HM. Changes in lymphoid tissue after treatment with a gonadotropin releasing hormone antagonist in the neonatal marmoset (Callithrix jacchus). AJRI 1998; 39:256-265 0 Munksgaard, Copenhagen PROBLEM: The effect of neonatal treatment with a gonadotropin releasing hormone (GnRH) antagonist on the morphology and distribution of lymphocytes in lymphoid tissue of the infant marmoset was examined. METHOD OF STUDY From a screened panel of antihuman antibodies for specific im- mune cells, antibodies for the CD20 and CD3 antigens showed excellent reactivity with marmoset tissue. Five sets of marmoset twins were treated with either the GnRH antago- nist or a vehicle from birth, and were euthanized at 7 to 9 (3 sets) or 16 to 20 weeks (2 sets) of age. The spleen, thymus, and inguinal lymph nodes from each animal were pro- cessed for immunocytochemistry, and the number of cells expressing the CD20 and CD3 antigens were quantified. RESULTS: Control twins exhibited high plasma levels of testosterone, characteristic of the neonatal period, whereas testosterone concentrations were reduced (P = 0.001) to de- tection limits in the GnRH antagonist-treated twins. Microscopic evaluation suggested that treatment reduced the volume and cellularity of the thymic cortex, resulting in a decrease in the cortical-to-medullary ratio. Treatment reduced (P = 0.046) the number of thymocytes expressing the B-cell antigen (CD20) and marginally lowered (P = 0.067) the number ex- pressing the T-cell antigen (CD3) in the thymic medulla. In the spleens of treated ani- mals, periarterial lymphatic sheaths were less prominent on microscopic examination, and there were marginally fewer (P = 0.064) CD3+ cells. Numbers of CD20+ lymphocytes in the peripheral white pulp of the spleen and in the germinal centers of the lymph nodes, or CD3+ cells in the paracortex and germinal centers of the lymph nodes, were not altered by treatment. CONCLUSION: Neonatal treatment with a GnRH antagonist may alter maturational processes for B and T cells in the thymus and spleen of the marmoset and may deprive the immune sys- tem of its normal sensitivity to GnRH at a potentially critical time in development. INTRODUCTION Key words: B cells, GnRH, immune-system development, infant primate, T cells DAVID R. MANN MUKAILA A. AKlNBAMl Department of Physiology, Morehouse School of Medicine Atlanta, Georgia SARAH HOWIE Department of Pathology, University of Edinburgh, Edinburgh, Scotland, UK DOUGLAS F. PAULSEN Department of Anatomy, Morehouse School of Medicine, Atlanta, Georgia STEPHEN F. LUNN HAMISH M. FRASER Medical Research Council Reproductive Biology Unit, Edinburgh, Scotland, UK Address reprint requests to David R. Mann, Department of Physiology, Morehouse School of Medicine, 720 Westview Drive, SW, Atlanta, GA 30310-1495. Submitted September 23, 1997; accepted October 3 1, 1997. Recent evidence supports the concept that an interaction between the immune and reproductive systems during development is essential for these systems to achieve zyxw 0 MUNKSGAARD, COPENHAGEN