Altered expression of CD11/CD18 on the peripheral blood phagocytes of patients with tuberculosis

Abstract

Tuberculosis (TB), caused by Mycobacterium tuberculosis, is characterized by granulomatous lesions made up of epithelioid cells, giant cells and mononuclear leucocytes. Cell-cell adhesion is important in granuloma formation and in the leucocyte migration which accompanies it. We have recently shown increased expression of the adhesion molecules CD11/CD18 (LeuCAMs, β2 integrins) on peripheral blood leucocytes from patients with sarcoidosis (Shakoor and Hamblin, 1992). Here we have studied the expression of CD11/CD18 and CD29 (VLA β1 integrin) on the peripheral blood leucocytes of 10 TB patients by flow cytometry. The density (expressed as mean fluorescence intensity) of CD11b on monocytes and polymorphs was increased (P < 0.005), as was CD11c (P < 0.005) and CD18 (P < 0.05) on polymorphs. CD11a expression was significantly reduced on polymorphs (P < 0.05). No differences were found in the expression of CD29, the percentages of cells expressing any molecule and, in contrast to sarcoidosis, the density of any molecule on lymphocytes. Although the cytokine tumour necrosis factor (TNF) has been implicated in the process of up-regulation, an ELISA for TNF failed to detect significant levels in plasma. The results suggest increased peripheral phagocyte CD11/CD18 expression is a feature of TB, which may contribute to the pathological processes involved.