Immunohistochemical Characterization of Monocytes-macrophages and Dendritic Cells Involved in the Initiation of the Insulitis and Beta-cell Destruction in NOD Mice

This immunohistochemical study describes the infiltration pattern of monocytes-macrophages and dendritic cells during the development of insulitis and diabetes in the NOD mouse. A panel of monoclonal antibodies (MoAbs) was used to analyze pancreases of nondiabetic (glucosuria negative) male and female NOD mice at 3, 7, 10, and 17 weeks of age. BALB/c female mice 17-weeks-old, diabetic NOD female mice 20- to 30-weeks-old, and nondiabetic NOD male mice 22-weeks-old were used as controls. Three MoAbs (viz., ER-MP23, MOMA1, and BM8) were special and appeared to identify macrophage/dendritic cell subsets that either had a characteristic infiltration pattern in the initial phases of the autoimmune reaction before T-cell infiltration or were typical for the later beta-cell destructive insulitis process. 1) Raised numbers of ER-MP23+ and MOMA-1+ dendritic cells/macrophages were characteristic for the initial phases of the NOD insulitis in 3-week-old mice. The cells were found in and near swollen para-insular vessels. In 7-week-old mice, these ER-MP23+ and MOMA-1+ cells had accumulated around the islets and were the first hematopoietic cells detectable at these spots. 2) From 7 weeks of age onward, BM8+ macrophages could be found in the para- and peri-insulitis processes. However, only in females were these BM8+ macrophages found to infiltrate into the islets. In lymphoid tissues, ER-MP23 predominantly reacts with macrophages/dendritic cells present in the subcapsular and interfollicular sinuses of lymph nodes and the T-cell zones of these lymph nodes. ER-MP23 also reacts with tissue macrophages/dendritic cells.(ABSTRACT TRUNCATED AT 250 WORDS)