NTU Undergraduates' research April 2014 - Biosciences | Page 60

The effectiveness of immunohistochemical stains in the identification of
Langerhans cells in Pulmonary Histiocytosis and their significance in the
detection of these cells in smokers and non-smokers
Hollie Bancroft
Nottingham Trent University

ABSTRACT
Pulmonary Langerhans cell histiocytosis (PLCH) is a rare idiopathic pulmonary disease, invariably associated with
cigarette smokers. PLCH is characterised by indistinct cystic, nodular, inflammatory lesions as a response to the
accumulation of Langerhans cells within the distil air spaces of the lung. Additional characteristic features include the
presence of eosinophils, alveolar macrophages and T-lymphocytes. CD1a and S-100 have traditionally been
recognised as the principle markers in the identification of Langerhans cells. In contrast, little is known about the
more selective langerin. In this study, the immunoreactivity of CD1a, S-100, and langerin was assessed. The purpose,
to establish the most effective diagnostic marker in the identification of Langerhans cells in PLCH. A total of 36 cases
were examined, 17 comprised of PLCH patients forming the test group with the remaining 19 non-smokers,
diagnosed with pneumothorax. Langerin revealed strong expression in the 13 test cases with the remaining 4
demonstrating moderate staining. CD1a and S-100 appeared to be equivalent in both groups, revealing a favourable
predominance to moderate expression. Of the control group, a high proportion of cases were negative for all 3
markers. However, equivocal, moderate, and strong staining was also observed, indicating a potential population of
Langerhans cells in the lungs of pneumothorax patients. Supportive findings were also found from complementary,
subordinate markers, CD68 and IgG4, highlighting the prevalence of pigmented alveolar macrophages and fibrosis
respectively. Overall, langerin appears to be the most statistically sensitive and specific marker in the detection of
Langerhans cells in smoking associated PLCH. Langerin is significantly effective in distinguishing PLCH from non-PLCH
conditions observed in non-smoking population.
Keywords: Langerhans cells, Pulmonary Histiocytosis, Dendritic cells, Alveolar macrophages, Cytokines, Smoking and
Immunohistochemistry