Nuclear bodies in mouse lymphoid cells stimulated by lipopolysaccharide

C57 BL/6J mouse spleen lymphocytes have been stimulated by a polyclonal mitogene, the lipopolysaccharide of E. coli (LPS). Depending on the LPS concentration, two pathways of B lymphocyte differentiation can be obtained. At low dose, the population is mainly composed of blast cells (85%) and at a high dose, the latter transforms into plasma cells (80%). Four types of nuclear bodies have been distinguished and quantitatively studied at several stages of cell differentiation. Only the simple nuclear bodies type A, which could be related to the nuclear matrix, show quantitative modifications in small lymphocytes. Connections between granular nuclear bodies (type D) and nucleolar material have been observed. Some granular nuclear bodies exhibit a morphological zone similar to the nucleolar fibrillar centre as well as fibrillar and granular components. Autoradiographic studies indicate that the granular nuclear bodies contain RNA synthesized elsewhere in the nucleus and that this RNA subsequently migrates to the cytoplasm. Furthermore connections between granular nuclear bodies and chromatin have also been observed.