SOCS in situ expression in tuberculous lymphadenitis in an endemic area.

BACKGROUND: The immune response to Mycobacterium tuberculosis is complex and multifactorial, the cytokine system being a major factor in M. tuberculosis immunity. AIM: To analyze the immunohistochemical aspects of tuberculous lymph nodes in immunocompetent patients and search for associations between SOCS and cytokine expression in human tuberculous lymphadenitis. METHODS: Thirteen lymph nodes were assayed by immunohistochemistry for SOCS-1 and 3, STAT-3, RANTES, MIP-1-alpha, ICAM-1, IFN-gamma as well as CD45RO, CD20, CD34, CD68, trypsin and lysozyme. Additionally, the RT in situ PCR was performed for SOCS-1 and 3 mRNA detection. RESULTS: Decreased MIP-1 alpha expression together with reduced SOCS-3 (p=0.042), lysozyme (p=0.024) and CD45RO (p=0.05) was observed in the TB lymph nodes compared to the control lymph nodes. In conclusion, the lymphadenitis due to M. tuberculosis was associated with a downregulation of memory T cells (CD45RO), activated lysozymes and SOCS-3 compared to controls, which may play a role in the long-term bacterial replication and altered immune modulation characteristic of the disease.