[Expression of Interleukin-6 and Its Clinicopathological Significance in Castleman's Disease]

Objective: To evaluate the expression of interleukin-6 (IL-6) and its clinicopathological significance in Castleman's disease (CD).

Methods: Clinical data and paraffin blocks of 92 CD patients and 20 cases of lymph node reactive hyperplasia (LRH) as a control group were collected from department of pathology of Peking University Health Science Center. The expression of IL-6 was detected by using immunohistochemical method.

Results: The 92 patients were composed of 42 multicentric variant (MCDs) and 50 unicentric variant (UCDs) clinically, and 30 hyaline-vascular variant (HV-CDs) and 62 plasma cell variant (PC-CDs) morphologically. None of them was positive for HIV tests. There were 56 males and 36 females, and their ages ranged from 4 years to 90 years with the median 41 years. IL-6 was expressed in 77 (83.7%) of 92 CD cases and 1 (5.0%) of 20 LRH cases. The expression rate of IL-6 was 90.5% in MCDs, 78.0% in UCDs, 93.6% in PC-CDs and 63.4% in HV-CDs, respectively. PC-CD cases showed a significantly higher expression rate of IL-6 than HV-CD cases (P = 0.001). All cases with positive IL-6 expression in plasmacytes were PC-CDs, showing obviously higher expression in MCDs than that in UCDs (P = 0.003). Compared with HV-CD cases, much more PC-CD cases showed IL-6 positivity in endothelial cells (P = 0.008). However, IL-6 was rarely expressed by both FDCs and macrophages, with only 3.3% and 10.9% positive cases, respectively. There are 53.2% (41/77) of the IL-6 positive cases and 20.0% (3/15) of IL-6 negative cases suffered from systemic symptoms, showing a significant difference between the two groups (P = 0.018). Cases with IL-6 expression in plasmacytes and macrophages were more likely to suffer from systemic symptoms, especially B type symptoms (P < 0.05).

Conclusion: There is a high expression rate of IL-6 in CD, which is different from LRH. The expression of IL-6 has close relationship with CD subtypes and the presence of systemic symptoms. In all, the evaluation of interleukin-6 is of great value to guide the diagnosis and therapy of CD.