Increased expression of IL-12 receptor mRNA in active pulmonary tuberculosis and sarcoidosis

Am J Respir Crit Care Med. 1999 Oct;160(4):1119-23. doi: 10.1164/ajrccm.160.4.9807120.


Cytokines have been implicated in the pathophysiology and development of pulmonary diseases such as tuberculosis and sarcoidosis. In particular, the numbers of cells expressing Th1-type cytokines such as IFN-gamma and IL-12 are increased within the lungs of patients with these granulomatous diseases. As a factor promoting the commitment of naive lymphocytes to a Th1-type profile of cytokine expression, IL-12 may be pivotal in the cascade of proinflammatory events within the airways. In this study, we examined the expression of the IL-12 receptor (IL-12R) mRNA in bronchoalveolar lavage (BAL) fluid from patients with active pulmonary tuberculosis (n = 6) and active pulmonary sarcoidosis (n = 6), and from allergic asthmatics (n = 6) and normal control subjects (n = 6). Bronchoscopy with BAL was undertaken, and cell cytospins were examined using the technique of in situ hybridization. There was a significant increase in the numbers of cells expressing mRNA for both beta(1) and beta(2) subunits of the IL-12R in active pulmonary sarcoidosis (p < 0.02, p < 0.01, respectively) and active pulmonary tuberculosis (p < 0.01, p < 0.005, respectively) compared with normal control subjects. In contrast, the allergic asthmatic patients exhibited a significant decrease in the number of IL-12R mRNA-positive cells (both beta(1) and beta(2) subunits (p < 0.01, p < 0.005, respectively), compared with the normal control subjects. These patients did, however, exhibit a significant increase in IL-4R mRNA, which was not evident in those with either tuberculosis or sarcoidosis when compared with normal subjects (p < 0.05). Colocalization studies demonstrated that CD8+ve cells are a principal site for the expression of IL-12R in tuberculosis. In sarcoidosis, IL-12R was expressed both on CD4+ve and CD8+ve cells. The increased expression of receptors for IL-12 in granulomatous diseases such as pulmonary tuberculosis and sarcoidosis provides evidence supporting the commitment of lymphocytes to a Th1-type cytokine profile in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Asthma / complications
  • Asthma / metabolism
  • Bronchoalveolar Lavage Fluid / cytology
  • CD4-Positive T-Lymphocytes / metabolism
  • CD8-Positive T-Lymphocytes / metabolism
  • Female
  • Humans
  • Hypersensitivity / complications
  • Immunohistochemistry
  • In Situ Hybridization
  • Male
  • Middle Aged
  • RNA, Messenger / analysis*
  • Receptors, Interleukin / genetics
  • Receptors, Interleukin / metabolism*
  • Receptors, Interleukin-12
  • Receptors, Interleukin-4 / genetics
  • Receptors, Interleukin-4 / metabolism
  • Sarcoidosis, Pulmonary / metabolism*
  • Tuberculosis, Pulmonary / metabolism*


  • RNA, Messenger
  • Receptors, Interleukin
  • Receptors, Interleukin-12
  • Receptors, Interleukin-4