Sarcoidosis is a multisystem granulomatous disease in humans with unknown aetiology and
no current definitive diagnostic method. Intradermal inoculation of Kveim reagent
(sarcoidosis tissue) was historically used for diagnosis, by causing a granuloma at injection
site within 4-6 weeks, with high sensitivity and specificity. The immune mechanisms of this
are poorly understood and the antigenic targets of granuloma-associated CD4+ T-cells are
unknown. This T-cell infiltrate is oligoclonal, implicating a small number of antigenic
targets. Previous work has shown that these are likely proteins.
Aim 1 of this project involved identification of candidate protein antigens within Kveim
reagent using proteomics, an established technology for the in depth quantitative differential
analysis of complex protein mixtures. These sarcoidosis-specific proteins were analysed using
gel electrophoresis with subsequent mass spectrometry and protein database interrogation.
More than 80 proteins were identified as appearing specific to Kveim reagent or of
significantly different abundance in sarcoidosis tissue compared to controls. These previously
unreported proteins represent novel information that may help in the further understanding of
the cellular pathways involved in disease.
Additionally, multiplex cytokine analysis was performed on supernatant from sarcoidosis
peripheral blood mononuclear cells incubated with both Kveim reagent and Kveim protein
fractions to identify a secreted Th1 signal specific to disease. Information from the
proteomics approach combined with this cytokine signal may be beneficial in creating an ex
vivo immune based assay for diagnosis.
Aim 2 of this project involved the direct analysis of serum and bronchoalveolar lavage (BAL)
fluid by multiplex cytokine analysis to investigate signals which could serve as diagnostic
biomarkers for the disease. BAL patterns in sarcoidosis were found indistinguishable from
tuberculosis but significantly different to healthy volunteers. Significant differences were also
found between sarcoidosis and tuberculosis serum, allowing for the creation of a model to
reliably distinguish between the two diseases.