ORGAN-CULTURE OF HUMAN LYMPHOID-TISSUE .1. CHARACTERISTICS OF THE SYSTEM

The major aim of three-dimensional tissue culture is to preserve the natural architecture of the tissue and thereby allow the cells to retain their original functions during in vitro cultivation. Here we describe a method for the rapid preparation of three-dimensional tissue explants from human lymphoid organs. The precision-cut tissue slices are of uniform size and thickness and can be cryopreserved and stored in liquid nitrogen without substantial loss of viability or functionality of the cells. Upon in vitro culture, cells within the explants survived as well as their counterparts cultured in single cell suspension. However, spontaneous immunoglobulin (Ig) production in explants started more promptly and often reached considerably higher levels than that in suspension cultures run in parallel. Lymphocytes within the slices could be activated by polyclonal stimuli such as PHA, as shown by the upregulation of the activation markers CD23 and CD25 on B and T cells, respectively. However, approximately five-fold higher concentrations of mitogen than those used for suspension cultures were needed. Taken together, the system presented here constitutes a potent tool for the investigation of the complex interactions leading to activation and differentiation of B and T cells in lymphoid organs.