Lymphocyte Subpopulations in NZB Mice: Deficit of Thymus-Dependent Lymphocytes

Abstract

The relative and absolute numbers of thymus-dependent lymphocytes (positive for ϑ isoantigen) and of thymus-independent lymphocytes (positive for membrane immunoglobulins or for antigen-antibody-complement receptors) were studied in the lymphoid tissues of NZB and CBA/H mice. The ages of the mice ranged from 100 to 600 days. A progressive decline of ϑ-positive lymphocytes was observed with age in NZB, but no such decay was detected in CBA/H mice, a non-autoimmune strain. The decline of ϑ-positive lymphocytes was observed in NZB mice as early as 200 days of age and appeared even in absence of detectable signs of autoimmunity, although the decline was accentuated by the development of autoimmunity and by progressive age. No such changes were observed for the thymus-independent lymphocytes, and only a moderate increase of these cells was observed with age both in NZB and CBA/H strains.