Isolation of the intact white pulp. Quantitative and qualitative analysis of the cellular composition of the splenic compartments

The spleen is anatomically and functionally divided into two compartments: the red pulp, where particles are effectively removed from the blood, and t he white pulp, where specific immune responses are generated. Here the isol ation of white pulp from red pulp is described, allowing a detailed analysi s of the cellular components of both red and white pulp separately. A strik ing abundance of memory T cells was found in the white and red pulp with an overall ratio of T and B cells in the white pulp being similar to that in lymph nodes. Both NK and gamma delta T cells can be found in white pulp and lymph nodes, but granulocytes are absent. The distribution of dendritic ce ll subsets showed significant differences between white pulp and lymph node s. Furthermore, short-term homing experiments showed that migration of lymp hocytes into the white pulp greatly exceeded that into lymph nodes, with si gnificant differences in migration of various lymphocytes subsets. This sug gests a different migration and retention mechanism in the white pulp. This new isolation technique will allow further analysis of the functional capa cities of the splenic compartments.