Genetic Control of Diabetes Induction by Complete Freund's Adjuvant Combined with Subdiabetogenic Doses of Streptozotocin in Lewis Rats - Evidence for Transient Cytotoxicity against Beta Cells

Abstract

The non-specific activation of the immune system by administration of complete Freund's adjuvant (CFA) was examined in two congenic Lewis rat strains LEW. 1A (RT1a) and LEW. 1W (RT1u) as a possible mean of amplification of the specific immune response, directed to pancreatic beta cells induced by multiple non-diabetogenic injections of streptozotocin (STZ). Rats were given intraperitoneally 0.5 ml CFA and 1 day later 25 mg/kg body weight STZ. This combined treatment was repeated twice at weekly intervals. Control groups received vehicle, STZ or CFA only with the same doses and at the same times. Only CFA/STZ-treated rats developed a persisting hyperglycaemia (greater than 15 mmol/l glucose) namely 3/18 (17%) LEW. 1W and 47/76 (62%) LEW. 1A rats. The pancreatic insulin content in these hyperglycaemic rats was reduced by 96.6% in LEW. 1A rats and by 93% in LEW. 1W rats measured 8 weeks after the last CFA/STZ treatment. The response to CFA indicated by an increase of number of peripheral leucocytes and relative spleen weight gain at 7 days after CFA administration, was higher in LEW. 1A rats compared with those of LEW. 1W rats. Spleen cells harvested 72 h/48 h after the first and second CFA/STZ administration showed a cytotoxic reaction to isolated syngeneic islets as measured by 51Cr-release in vitro. Control rats receiving vehicle, STZ or CFA only showed no cellular anti-islet cytotoxicity. The anti-islet cytotoxicity of spleen cells was only transient and disappeared after the third CFA/STZ administration. Anti-islet cytotoxic antibodies were not detectable in this short-term study.(ABSTRACT TRUNCATED AT 250 WORDS)

The Possibility that Pancreatic Beta Cell Destruction Leading to Type 1 Diabetes is Initiated by the Release of Cytokines by Polyclonal Activation of the Immune System*)

“…We have recently demonstrated a permanent pancreatic insulin loss and complementdependent cytotoxicity against beta cells induced by only polyclonal activation of the immune system (Ziegler et al, 1984a) in Wistar rats by administration of complete Freund's adjuvant (CFA). The pancreatic insulin loss was associated with the extent of the genetically controlled polyclonal activation (Ziegler et al, 1987). In this article, supported by new data, we propose a modified etiopathogenesis concept of type 1 diabetes.…”

Survival af Islet Isografts Despite Cytotoxicity against Pancreatic Islets Measured in Vitro*)

“…this inflammation was unrelated to hyperglycaemia. CFA did not induce an insulitis in rats (Kohnert et al, 1987) and did not increase the incidence or severity of insulitis in mice (Richeris et al, 1987). CFA caused an activation of macrophages producing cytokiries known to be toxic to beta cells (Schwizer et al, 1984;Mandrup-Poulseri et al, 1985;Beiidtzen et al, 1986) which may act synergistically with STZ.…”

“…The cytotoxicity assay was considered positive if the 51Cr-release was greater than the basal 51Cr-release + 2 SD as measured with serum plus effector cells from vehicle-treated rats. 1) Kind donation from Dr. W. Dulin, Upjohn, Kalamazoo, Michigan, USA inflammatory lesions following the CFA injections (Kohnert et al, 1987). Already after the first combined CFA/STZ treatment, isolated splenocytes caused cytotoxicity against syngeneic islets in vitro, which may indicate that direct cell-mediated autoimmune phenomena play a role in the beta cell destruction in this diabetic model (Ziegler, B. et al, 1987a).…”

“…The CFA/STZ-treated rats developed a persistent hyperglycaemia; their pancreata showed a substartial loss of beta cells and the pancreatic insulin content was reduced by 96%. The exocrine parenchyma exhibited severe *) Dedicated to Professor H. Bibergeil on the occasion of his 65th birthday inflammatory lesions following the CFA injections (Kohnert et al, 1987). Already after the first combined CFA/STZ treatment, isolated splenocytes caused cytotoxicity against syngeneic islets in vitro, which may indicate that direct cell-mediated autoimmune phenomena play a role in the beta cell destruction in this diabetic model .…”

“…As originally demonstrated by Like and Rossini (1976) a slowly developing hyperglycaemia can be induced in certain mouse strains by the administration of repeated sbdiabetogenic doses of streptozotocin (STZ). We have recently reported that the administration of multiple subdiabetogenic doses of STZ given in weekly intervals produced asevere hyperglycaemia in susceptible rat strains only if the polyclonal activator complete Freund's adjuvant was given 24 h prior to the STZ injection , Ziegler et al, 1987a. The CFA/STZ-treated rats developed a persistent hyperglycaemia; their pancreata showed a substaitial loss of beta cells and the pancreatic insulin content was reduced by 96%.…”