Fig 2: CB2 immunoreaction in spleen and liver of a healthy control dog.A) CB2 is expressed in numerous leukocytes in the marginal zone (macrophages, dendritic cells, transit B and T cells) and mantel zone (T cells) of splenic follicle (white pulp) whereas few positive cells are seen in the germinal center (B Cells). B) Insert/Close up of the marginal and mantel zone of splenic follicle showing numerous CB2 positive leukocytes (arrow). C) CB2 is abundantly expressed in hepatocytes and Kupffer cells as well as slightly in endothelial cells while tunica media and adventitia remain negative. D) Insert depicting CB2 positive Hepatocytes and Kupffer cells. G: Germinal center; MZ: mantel zone; MarZ: marginal zone. IHC was performed using the avidin-biotin-peroxidase complex (ABC) method.

Fig 3: CB2 immunoreaction in spinal cord sections of dogs with SRMA, IS and healthy controls.A) Detail of blood vessel and meninges of a healthy dog, notice lack of immunoreaction in the adventitia, endothelial cells, flat mesothelial-like arachnoid membrane cells and pia matter cells. B) Blood vessel of a dog with SRMA characterized by strong perivascular and subarachnoidal CB2 positive inflammatory infiltrates and slight to moderate CB2 immunoreaction within the smooth muscle cells of the tunica media. C) Blood vessel of a dog with IS, slight CB2 immunoreactivity is seen in the tunica media of the vessel whereas perivascular inflammatory infiltrates show strong immunoreaction. D) Detail of glial cells in the white mater of a healthy dog with moderate to strong intracytoplasmic CB2 immunoreaction. E) Strong CB2 immunostaining is shown in round glial cells within the white matter of a dog with SRMA. F) Strong CB2 immunoreaction in astrocytes within the white matter of a dog with IS. G) Moderate to strong immunolabeling of astrocytes and slight immunolabeling of neurons with CB2 antibody within the grey matter of a healthy dog. H) Moderate CB2 immunostaining is shown in the cytoplasm of a neuron and adjacent glial cells within the grey matter of a dog with SRMA. I) Strong spotted CB2 immunoreaction in the cytoplasm of neurons within the grey matter of a dog with IS. IHC was performed using the avidin-biotin-peroxidase complex (ABC) method.

Fig 4: Immunohistochemistry of anti-CB2 antibody in spinal cord SRMA lesions.A) Strong CB2 positive perivascular inflammatory infiltrates surrounding meningeal blood vessels. B) The CB2 positive leukocyte population mainly consists of lymphocytes, plasma cells and fewer macrophages. C) Severe diffuse infiltration of the dura mater with CB2 positive inflammatory cells. D) Vacuolization of white matter areas with concomitant CB2 positive glial cells and leukocytes. IHC was performed using the avidin-biotin-peroxidase complex (ABC) method.

Fig 5: Immunohistochemistry of anti-CB2 antibody in spinal cord lesions of dogs with intraspinal spirocercosis.A) Notice moderate to strong CB2 immunostaining of swollen axons (spheroids) within the white matter. B) Prominent intracytoplasmic staining of large foamy macrophages (gitter cells) with CB2 antibody. C) Severe diffuse infiltration of the subarachnoidal space with strongly CB2 labeled inflammatory cells. D) The CB2 positive leukocyte population mainly consists of macrophages and fewer lymphocytes and plasma cells. IHC was performed using the avidin-biotin-peroxidase complex (ABC) method.