Bilateral dissected spleens and thymuses in rodents exhibit homogeneity inleukocyte markers

Histopathologic evaluation and/or archiving of sections of spleen or thymus from all study animals may be mandated by study protocol (e.g., Toxic Subs tances Control Act-compliant studies). In such cases, whole spleen or thymu s is not available for immunophenotyping. It has not been previously demons trated that immunologic data representative of whole organs can be reliably obtained using a section of the spleen or using one thymic lobe. Light-sca tter characteristics and immune cell-surface antigen expression were theref ore compared in the right and left halves of the spleen and in the right an d left thymic lobes of young adult female C57B1/6 mice and Sprague-Dawley r ats. Antigens compared were: mouse spleen - CD11b, CD45R, CD90; rat spleen - CD11b, CD45RA, Pan-T/Ox-52; mouse and rat thymus - CD4, CD8a. There were no significant differences in distribution of cells by size or by expressio n level for any of these antigens when the right part of the organs was com pared to the left part. These data indicate that use of entire spleen or bo th thymic lobes is not required to reliably quantify resident immune cell s ubpopulations. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.