Cloning, expression, and purification of rat IFN-alpha 1

Potential role of autoantibodies in the regulation of cytokine responses during bacterial infections

An immunoregulatory mechanism involving release of neutralizing autoantibodies (Aabs) to self cytokines during bacterial infections is presented herein. Intraperitoneal inoculation of Haemophilus influenzae type b into Sprague-Dawley rats resulted in a self-limiting meningitis. High levels of cells expressing mRNA for gamma interferon (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha) were detected 12 to 48 h postinoculation (p.i.) in splenocytes, and large numbers of IFN-gamma-secreting cells were present in the spleen on day 3 p.i. These levels were undetectable at days 9 and 14 p.i. Increased titers of Aabs of immunoglobulin G (IgG) isotypes to both cytokines were observed, with a peak at day 7 p.i. and with very low levels at day 30. Upon reinoculation with H. influenzae type b at day 30, regeneration of Aabs was recorded 7 days later (i.e., at day 37). To elucidate their regulatory importance, Aabs dose-dependently inhibited IFN-gamma production by splenocytes, IFN-gamma-induced major histocompatibility complex expression by peritoneal macrophages, and TNF-alpha-induced thymocyte proliferation. To control the specificity of these Aabs, Fab fragments of purified serum Igs from day p.i. exhibited binding and neutralizing effects. Furthermore, preincubation of the sera with a cytokine inhibited the binding and neutralization effects of that particular cytokine, but not those of any other cytokine. Aab-producing B cells were cloned, and their supernatants had similar effects. Our data suggest a role for autoimmunity in cytokine regulation and suggest that a maintained balance of this mechanism may protect from sequelae.

The effects of 5-fluorouracil and interferon-alpha on early healing of experimental intestinal anastomoses

The continuing search for effective adjuvant therapy after resection of intestinal malignancies has prompted a growing interest in both immediate post-operative regional chemotherapy and the combination of 5-fluorouracil (5-FU) and interferon-alpha as drugs of choice. We have compared the effects of both compounds, alone and together, on early healing of intestinal anastomoses. Four groups (n = 26 each) of rats underwent resection and anastomosis of both ileum and colon: a control group and three groups receiving intraperitoneal 5-FU, interferon-alpha or both on the day of surgery and the next 2 days. Animals were killed 3 or 7 days (n = 10 each) after operation in order to measure anastomotic strength and hydroxyproline content. The remaining six animals in each group were used to study anastomotic collagen synthetic capacity at day 3. Three days after operation, ileal anastomotic bursting pressure was lowered by 37% in the 5-FU/interferon-alpha group (P = 0.0104). At day 7, anastomotic breaking strength was reduced significantly in ileum (P = 0.0221) and colon (P = 0.0054) of the 5-FU/interferon-alpha group and in colon of the interferon-alpha group (P = 0.0221). Collagen synthetic capacity was strongly suppressed by 5-FU but not by interferon-alpha. However, no differences in anastomotic hydroxyproline content were observed between groups at both days 3 and 7. Thus, post-operative use of interferon-alpha, in particular in combination with 5-FU, may be detrimental to anastomotic repair in the intestine.

Both CD4+ and CD8+ T cells are essential to induce experimental autoimmune myasthenia gravis

CD4+ T cells have been shown to be crucial in the development of experimental autoimmune myasthenia gravis (EAMG). The role of CD8+ T cells in EAMG is less well established. We previously showed that antibody depletion of CD8+ T cells in rats effectively suppresses EAMG. To further study the role and relationship of CD4+ versus CD8+ T cells in induction of EAMG, CD4-/-, CD8-/-, and CD4-8- mutant C57BL/6 mice and the parent CD4+8- wild-type mice were immunized with Torpedo acetylcholine receptor (AChR) plus complete Freund's adjuvant. Clinical EAMG was nearly completely prevented in CD4-8-, CD4-/-, and CD8-/- mice. This was associated with strongly reduced AChR-specific T and B cell responses, and with reduced levels of AChR-reactive interferon gamma (IFN-gamma) and interleukin 4 (IL-4) mRNA-expressing cells in lymphoid organs when compared with CD4+8+ wild-type mice. We conclude that (a) both CD4+ and CD8+ T cells are essential for development of EAMG, and a collaboration between these cell types may be necessary; (b) CD4+ as well as CD8+ T cells secrete IFN-gamma and IL-4, and both cytokines are involved in the development of EAMG; and (c), besides T cells, other immune cells might also be responsible for help of anti-AChR antibody production.