Alteration in DNA synthetic response of thymocytes from NZB mice of different ages

Migration of carbon-laden peritoneal macrophages into the thymus of autoimmune New Zealand mice

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Treatment of NZB/NZW F1 hybrid mice with Mycobacterium bovis strain BCG or type II interferon preparations accelerates autoimmune disease

NZB/NZW F1 hybrid mice develop a spontaneous autoimmune disease characterized by the appearance of antinuclear antibodies and premature death due to immune complex glomerulonephritis. To investigate the possible effects of cellular immune stimulation on this disorder, groups of female NZB/NZW mice, aged 2, 5, and 7 months, were treated either with the nonspecific immunostimulatory agent Mycobacterium bovis strain BCG or with saline. Mice treated with BCG at ages 5 and 7 months died sooner than age-matched controls, and death was associated with severe glomerulonephritis, suggesting that BCG may have accelerated autoimmunity in these mice. Since BCG is known to stimulate the production of type II (or gamma) interferon, a substance with potent immunoregulatory effects, a second study was carried out to assess the effects of type II interferon on NZB/NZW disease. A greater number of type II interferon-treated mice died by 9 months of age when compared to controls, and the increased death rate was associated with a more rapid development of antinuclear antibodies and histologically confirmed glomerulonephritis. These data, together with a recent report of increases in the level of serum type II interferon in patients with active systemic lupus erythematosus, suggest that type II interferon may play a role in the pathogenesis of autoimmune disease.

Loss of suppressor T cells in the pathogenesis of the autoimmunity of NZB/W mice

Loss of suppressor T cells was demonstrated in NZB/W mice, an animal model of autoimmunity. As NZB/W mice matured they lost splenic T cells that could be activated by concanavalin A (Con A) to become suppressor cells and lost the ability to produce the regulator of humoral immune responses, soluble immune response suppressor (SIRS). However, NZB/W spleen cells retained the capacity to respond to suppressor signals from Con A pulsed normal spleen cells. Thrice weekly administration of SIRS containing supernatants of Con A pulsed normal spleen cells to young NZB/W mice lead to a striking reduction in the manifestations of autoimmunity.

Association of defective feedback suppressor T cell activity with autoimmunity in NZB mice

A "feedback suppressor T cell" highly dependent on signals from Ly 1 T helper cells for activation is described. The signal from the Ly 1 cell binds to Fc-like receptors on macrophage membranes. The feedback suppressor cell expresses all three Ly antigens as well as the Qa 1 antigen on its surface, is very sensitive to low doses of cyclophosphamide, disappears relatively rapidly after adult thymectomy, and cannot be demonstrated in NZB mice 6 weeks or older.

Independent appearance of anti-thymocyte and anti-RNA antibodies in NZB/NZW F1 mice

NZB and NZB/NZW (B/W) mice were studied for natural thymocytoxic autoantibody(NTA) and antibody to reovirus RNA by cytotoxicity and radioimmunoassay respectively.NZB mice developed NTA by 2-3 months of age. RNA antibodies appeared later if atall. NTA and anti-RNA were present in B/W mice starting at 4-5 months and increased in frequency with age. Either activity could appear first and could be present without the other. Thus, all four possible patterns of autoantibody occurrence were found. NTA and anti-RNA in 12-month B/W sera were separable by sucrose density gradient ultracentrifugation; NTA is a 19S IgM antibody whereas anti-RNA is 7S.

Thymosin-induced reduction of "null cells" in peripheral-blood lymphocytes of patients with systemic lupus erythematosus

Although thymosin, a thymic hormone, has been shown to restore cellular immunity in NZB/NZW mice, its effect in human systemic lupus erythematosus (S.L.E.) and other auto-immune disorders has not been tested. The present study shows for the first time that the proportion of "null cells" in peripheral-blood lymphocytes of patients with active S.L.E. is significantly decreased after in-vitro thymosin treatment. Thymosin has no effect on the percentages of T cells, B cells, and "null" cells in peripheral-blood lymphocytes from normal controls and patients with inactive S.L.E. and active rheumatoid arthritis. These findings suggest that thymosin may play an important part in the pathogenesis and treatment of this condition.

Thymosin corrects the abnormal DNA synthetic response of NZB mouse thymocytes

New Zealand Black (NZB) mice develop after 16 weeks of age an autoimmune and lymphoproliferative disease which is a model for systemic lupus erythematosus and lymphoid malignancy in humans. At this age, the mice manifest a progressive decline in T lymphocyte (thymus-derived lymphocyte) functions and serum thymosin levels. Thymocytes from 8-week old NZB mice exhibit an abnormal DNA synthetic response when transplanted into lethally irradiated C57B1/6 recipients. DNA synthesis (measured as the incorporation of radioactively labeled 5-iodo-2'-deoxyuridine) is delayed in onset and still increasing 6 days after cell transfer. By contrast, 2-week old NZB thymocytes show a normal response which is rapid in onset and completed by day 6.NZB mice were injected with thymosin fraction 5 or with bovine serum albumin starting at 2 weeks of age. Thymocytes from 8-week old thymosin-treated mice showed a normal DNA synthetic response, whereas the albumin-treated controls showed the abnormal response expected at this age. The ability of thymosin to correct the DNA synthetic response was related to dose and duration of treatment. These results suggest that thymosin can induce a more normal state of thymocyte differentiation in NZB mice. If abnormal thymocyte differentiation is related to the subsequent emergence of autoimmunity and lymphoid malignancy, then continuous treatment with thymosin may have therapeutic potential. These experiments suggest that an endocrine disturbance may contribute to autoimmune and lymphoproliferative disease in NZB mice and possibly in humans.