Breakdown of the blood-retinal barrier induced by activated T cells of nonneural specificity.
The cellular and microvascular responses of JC Lewis rats to an intravenous injection of activated T cells specific for ovalbumin were examined with the retinal whole mount technique. The retina was examined at various times post-injection (pi) with the use of antibodies to the alphabeta T cell receptor (TCR) or to major histocompatibility complex class II (MHC II), the monoclonal antibody ED1, and intravascular tracers. By 12 hours pi, small numbers of TCR(+), ED1(+), and MHC II(+) cells were present within the lumen of retinal vessels, and minor breakdown of the blood-retinal barrier (BRB) and microglial activation were evident. The intensity of these responses had increased by 1 day pi, when small numbers of TCR(+) cells had also undergone extravasation. By 2 to 3 days pi, the numbers of TCR(+), ED1(+), and MHC II(+) cells in the retinal parenchyma had increased, but the BRB breakdown and microglial activation had subsided. Thus, in the absence of target antigen, activated T cells induced limited and transient breakdown of the BRB, microglial activation, and the extravasation of ED1(+), MHC II(+) monocytes. In contrast, the retina of rats that received an intraocular injection of ovalbumin in addition to the intravascular injection of T cells showed massive cellular recruitment and breakdown of the BRB. These results indicate that an increase in the number of activated T cells in the circulation, such as that which occurs during viral or bacterial infection, has the potential to result in transient breakdown of the BRB and a mild local microglial response.
Hu
P
P
Department of Anatomy and Histology and Institute of Biomedical Research, University of Sydney, Sydney, New South Wales, Australia.
Pollard
J D
JD
Chan-Ling
T
T
D000818:Animals; D000941:Antigens / Q000502:physiology; D001813:Blood-Retinal Barrier / Q000502:physiology*; D002199:Capillary Permeability / Q000502:physiology; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D008213:Lymphocyte Activation / Q000502:physiology*; D008297:Male; D051379:Mice; D017628:Microglia / Q000502:physiology; D010047:Ovalbumin / Q000276:immunology; D051381:Rats; D011917:Rats, Inbred Lew; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism; D012171:Retinal Vessels / Q000378:metabolism / Q000502:physiology; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology*; D014680:Veins
D000941:Antigens; D000949:Histocompatibility Antigens Class II; D016693:Receptors, Antigen, T-Cell, alpha-beta; D010047:Ovalbumin