Effect of altered lymphocyte function on immunologic disorders in NZB/NZW mice. III. Acceleration of disease by thymosin.

Administration of thymosin fraction V to NZB/NZW F1 mice, an animal model for human SLE, accelerated the appearance of proteinuria and anti-nDNA antibodies, increased deposition of immunoglobulins in kidneys, and significantly shortened survivals. Although the addition of thymosin to in vitro cultures of spleen and lymph node cells from thymosin-treated mice increased DNA synthesis in response to stimulation with Con A, in vivo treatment with thymosin did not affect the Con A response. There was no effect on in vitro responses to PHA or LPS, or on IgM antibody formation to SRBC (T cell dependent) or SSS III (T cell independent) immunizations. Antibodies to thymosin or contamination of our thymosin preparations with nucleic acids could not be demonstrated. The acceleration of autoimmune disease produced by thymosin treatment could not be explained by alteration of the T and B cell functions studied.