Diverse Immune Environments in Human Lung Tuberculosis Granulomas Assessed by Quantitative Multiplexed Immunofluorescence
Marta Abengozar-Muela (1), María Villalba Esparza (1, 2, 3), David Garcia-Ros (1, 2, 4), Cindy Estefanía Vásquez (4), José I Echeveste (1, 2) , Miguel Angel Idoate (1, 2), Maria D Lozano (1, 2, 3), Ignacio Melero (2, 3, 5, 6), Carlos E de Andrea (7, 8, 9, 10)
The precise nature of the local immune responses in lung tuberculosis (TB) granulomas requires a comprehensive understanding of their environmental complexities. At its most basic level, a granuloma is a compact, organized immune aggregate of macrophages surrounded by myeloid, B and T cells.
We established two complementary multiplex immunolabeling panels to simultaneously evaluate the myeloid and lymphocytic contexture of 14 human lung TB granulomas in formalin-fixed paraffin-embedded tissue samples.
We observed diverse CD3+ and CD8+ T-cell and CD20+ B lymphocyte compositions of the granuloma immune environment and a relatively homogeneous distribution of all myeloid cells. We also found significant associations between CD8+ T-cell densities and the myeloid marker CD11b and phagocytic cell marker CD68. In addition, significantly more CD68+ macrophages and CD8+ T cells were found in Mycobacterium tuberculosis-infected granulomas, as detected by Ziehl-Neelsen staining. FOXP3 expression was predominately found in a small subset of CD4+ T cells in different granulomas.
As the success or failure of each granuloma is determined by the immune response within that granuloma at a local and not a systemic level, we attempted to identify the presence of reactive T cells based on expression of the T-cell activation marker CD137 (4-1BB) and programmed cell death-1 (PD-1). Only a small fraction of the CD4+ and CD8+ T cells expressed PD-1. CD137 expression was found only in a very small fraction of the CD4+ T cells in two granulomas.
Our results also showed that multinucleated giant cells showed strong PD-L1 but not CTLA-4 membrane staining. This study offers new insights into the heterogeneity of immune cell infiltration in lung TB granulomas, suggesting that each TB granuloma represents a unique immune environment that might be independently influenced by the local adaptive immune response, bacterial state, and overall host disease status.
CITATION Mod Pathol . 2020 Jun 26. doi: 10.1038/s41379-020-0600-6