Figure 9. MHC-I expression increases in infected astrocytes during an antiviral immune response, but does not show any particular pattern of distribution in relation to T cells' contacts.

(A) shows representative confocal images of non-contacted (top row) and contacted cells (bottom row) stained with DAPI (blue), and immunolabeled with markers of viral infection (TK, green), MHC-I (red), and activated astrocytes (GFAP, magenta). The fourth panel in each row shows an overlapping image of TK and MHC-I (TK MHC-1), of which the fifth panel is a higher magnification of the white boxed area. The last panel is a superposition of all four color channels (MERGE). MHC-I is expressed at high levels in virally infected astrocytes in contact with T cells. Note that presumed leukocytes (identified by the absence of TK, or GFAP immunoreactivity, ‘L’) display intense MHC-I immunofluorescence. Nuclei of virally infected astrocytes are indicated by (yellow) ‘A’. (B) shows the relative quantification of MHC-I fluorescence along protrusions (top panels) or processes (bottom panels) of contacted cells. Illustrations on the left indicate the morphological position of the measurements analyzed (with respect to the nucleus). Fluorescence intensity graphs in the center display relative MHC-I immunofluorescence (measured from the cell body to the cell periphery along the arrows indicated in the left panels). MHC-I intensity on both sides (M1 and M2) and cytoplasm (C) of virally infected cells is shown. Analysis of relative fluorescence on the right shows the average intensity of MHC-I expression in proximal, medial and distal areas, relative to the nucleus. The fluorescence intensity of 30 cells was measured. The expression of MHC-I follows a proximo-distal pattern of intensity.