Biology of isolate immunocytes. III. Fine immunocytological characterization of lymphoplasma cells.

A system for characterization of lymphoplasma cells based on ultrastructural, immunocytological and autoradiographic data is proposed. It is composed of six cell types and transitional forms. Any mouse lymphocyte can be classified within one of these forms and the lymphocytes of a lymphoid organ may be subdivided into populations of characteristic cells. The cell types are defined as follows: 1) the differentiated Ig lymphocytes which bear Ig at their surface, have a rough nuclear sap, a granular cytoplasm and often show mcrovilli at the cell surface; none of these lymphocytes incorporate thymidine and therefore this subpopulation can be considered as mature; 2) the differentiated plasmacytes have a well organized rough endoplasmic reticulum; differentiated plasmacytes are not 3H-thymidine labelled and this subpopulation is mature; 3) the differentiated T lymphocytes with theta-antigen at their cell surface contain a smooth endoplasmic reticulum, a developed Golgi apparatus and lysophagosomes; the differentiated T lymphocytes show no 3H-thymidine labelling and this subpopulation is also mature; 4) in the large lymphocytes without surface Ig nor theta-antigen, chromatin aggregate are intermingled to the nuclear sap and a large nucleolus is present; this subpopulation of lymphocytes, a number of which show usually 3H-thymidine labelling, is immature; 5) the small lymphocytes without surface Ig nor theta-antigen have a large nuclear cytoplasm ratio; like the large lymphocytes, this population is also immature, since a percentage of these cells usually incorporates thymidine; 6) small T lymphocytes are labelled by the theta-antigen marker; after antigenic stimulation some of them are found to incorporate thymidine. Transitional forms between two cell types are also observed. They are more numerous immunization. This system of cell characterization is an attempt to correlate structure with function of lymphocytes withing the T and B cell concept of experimental immunology.