Immune cells in the porcine retina: distribution, characterization and morphological features.
OBJECTIVE
To investigate the presence of immunocompetent cells in the porcine retina and to compare the findings with those obtained earlier in human retinas.


METHODS
Retinal wholemounts or cryostat sections from outbred Dutch Landrace pigs were analyzed for the presence of microglia (CD45), macrophages-monocytes (SW3, CD163, 2A10, CD14), major histocompatibility complex (MHC) class II-positive cells (MCA1335), granulocytes (MCA1219), B lymphocytes (IgM), and T lymphocytes (CD6, CD4, CD8), by using specific monoclonal antibodies followed by immunohistochemical staining.


RESULTS
A uniform distribution of CD45-positive microglial cells was observed throughout the porcine retina (mean number, 289 +/- 16 cells/mm(2)). The microglia were observed along blood vessels and within the tissue between the inner limiting membrane and the inner nuclear layer. MHC class II-positive cells were mainly observed along the large- and middle-sized retinal blood vessels. Double-staining experiments showed that 54% of the microglial cells lining the larger retinal vessels were MHC class II positive. Macrophages were only incidentally observed along the larger retinal blood vessels. No T lymphocytes, B lymphocytes, monocytes, or granulocytes were observed within the retinal tissue.


CONCLUSIONS
The porcine retina contains a rich network of microglial cells. Approximately half of the microglial cells lining the larger retinal vessels express MHC class II. The normal porcine retina is devoid of lymphocytes, monocytes, and granulocytes. The distribution of immunocompetent cells in the porcine retina largely resembles that observed in the human retina.
Yang
Peizeng
P
Zhongshan Ophthalmic Center, Sun Yat-sen University of Medical Sciences, Guangzhou, Peoples Republic of China.
Chen
Ling
L
Zwart
Rob
R
Kijlstra
Aize
A
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D001402:B-Lymphocytes / Q000166:cytology / Q000378:metabolism; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D007107:Immune System / Q000166:cytology*; D007124:Immunoenzyme Techniques; D007962:Leukocytes / Q000166:cytology* / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D009000:Monocytes / Q000166:cytology / Q000378:metabolism; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism; D012160:Retina / Q000166:cytology*; D013552:Swine / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism
D015703:Antigens, CD; D000949:Histocompatibility Antigens Class II