EFFECT OF INTERLEUKIN-1A, IL-1B AND IL-1 RECEPTOR ANTIBODY ON THE PROLIFERATION AND STEROIDOGENESIS OF REGENERATING RAT ADRENAL-CORTEX

Several data suggest that the endocrine and immune systems are closely interconnected, therefore, we investigated the effect of interleukin- l on adrenocortical regeneration. The study was performed on adult rat s subjected to left adrenal enucleation combined with contralateral ad renalectomy. The animals were given purified human recombinant IL-1alp ha (5 mu g/kg), IL-1beta (5 mu g/kg) anti-human IL-1 receptor antibody (10 mu g/kg) and combination of interleukins and antibodies. The cell proliferation measured by bromodeoxyuridine incorporation and plasma corticosterone determined by a RIA kit were evaluated six days after o peration. The mean cell growth ratio expressed as number of BrdU-posit ive cells per 1,000 cells was 11.86 +/- 0.45 in the control group. IL- lb significantly stimulated the proliferation ratio (15.30 +/- 0.88; p < 0.01) and this effect could be prevented by addition of IL-1rAb. Th e antibody caused also a well-marked inhibition of cell growth ratio ( 8.23 +/- 0.67; p < 0.01). The plasma corticosterone concentration was higher in IL-lb-treated animals than in the control group, 107.79 +/- 2.82 vs. 61.08 +/- 2.0 ng/ml, respectively, p < 0.01. On the other han d, IL-1rAb decreased corticosterone secretion (31.53 +/- 2.58 ng/ml, p < 0.01) and reversed the stimulatory effect of of IL-lb. In contrast, IL-la seemed to have no influence on adrenocortical regeneration. In conclusion, this study supported the thesis of close interconnection b etween immune and endocrine systems and revealed that IL-lb could act as a growth-promoting factor on regenerating adrenal cortex in the rat .