Macrophages and dendritic cells infiltrating islets with or without beta cells produce tumour necrosis factor-alpha in patients with recent-onset type 1 diabetes

Abstract

Aims/hypothesis: Type 1A diabetes results from autoimmune destruction of pancreatic beta cells. We examined the involvement of TNF-alpha and IL-1beta, as well as of T cells, macrophages and dendritic cells, in the destruction of beta cells in patients with recent-onset type 1 diabetes.

Materials and methods: We obtained pancreatic biopsy specimens from six patients with recent-onset type 1 diabetes and analysed these by immunohistochemistry.

Results: T cell infiltration was less common in islets without beta cells (12.5 [0-33.3]%) than in those with beta cells (46.0 [17.4-83.3]%), while macrophages and dendritic cells showed a similar extent of infiltration into islets both with or without beta cells. TNF-alpha was detected in 25.0 (4.3-46.9)% of macrophages and 11.8 (0-40.0)% of dendritic cells infiltrating the islets in samples from each patient, but not at all in T cells. IL-1beta was detected in 1.8 (0-11.3)% of T cells infiltrating the islets with beta cells, while it was found in 19.2 (0-35.3)% of macrophages or 10.7 (0-31.3)% of dendritic cells infiltrating the islets in samples from each patient (all values median [range]).

Conclusions/interpretation: Macrophages and dendritic cells infiltrate the islets and produce inflammatory cytokines (TNF-alpha and IL-1beta) during the development of type 1A diabetes.