Figure 4.

Preferential generation of L. donovani foci within the schistosome egg granulomatous tissue. A: Liver sections from S/L mice at +8 weeks after co-infection were stained for L. donovani amastigotes using immune hamster anti-L. donovani serum and Alexa Fluor 546 goat anti-hamster IgG (red, arrow, AM) and for mannose receptor (MR) with anti-CD 206 and Alexa Fluor 488 goat anti-rat IgG (green). To ensure staining specificity, liver sections from the same S/L mice were stained with isotype control rat IgG2a (control for the MR staining) or normal hamster serum (control for the amastigote staining). No nonspecific staining was seen. Strong specific MR staining can be seen in the granulomatous tissue surrounding the S. mansoni eggs (arrow, EG). The parenchymal Küpffer cells stain weakly for MR (arrow, KC), and MR-positive cells are absent from the granulomas surrounding L. donovani amastigotes in the parenchyma (inset). A higher density of red-staining L. donovani amastigotes can be seen in foci of L. donovani infection in the periphery of the S. mansoni egg granulomas compared with inside the L. donovani granulomas (LG) in the parenchymal tissue. B: This was confirmed quantitatively in H&E-stained tissue sections by counting the density of L. donovani foci in the egg granulomatous tissue of S/L mice (S/L G, open square) compared with the surrounding parenchyma (S/L P, filled square) and the parenchyma of L mice (L, open circle). For each mouse 50 adjacent fields were counted at ×400 magnification. The data in B show the mean ± SE from five mice per group and is representative of two separate experiments. *P < 0.01 for S/L G versus L; **P < 0.0001 for S/L P versus L; ***P < 0.0001 for S/L G versus L, P < 0.005 for S/L G versus S/L P. Original magnifications: ×100 (A); ×400 (A, inset).