Altered L-selectin expression in lymphocytes and increased adhesion to endothelium in patients with diabetic retinopathy.
OBJECTIVE
To investigate L-selectin expression and shedding in patients with and without retinopathy and to determine if any observed changes are reflected by a functional change in the adhesion of leucocytes to an endothelial monolayer.


METHODS
Age matched diabetic patients (26 with retinopathy, 19 without retinopathy) were compared to 24 non-diabetic controls to determine L-selectin surface protein expression, L-selectin mRNA production, and serum L-selectin levels by flow cytometry, RT-PCR, and ELISA, respectively. An adhesion assay was used to determine the binding of lymphocytes from the respective test groups to a monolayer of human endothelial cells.


RESULTS
Significantly reduced (p = 0.004) L-selectin expression was demonstrated on lymphocytes (CD3+) from patients with diabetes compared to controls, the lowest levels being found in those with diabetic retinopathy (p = 0.004). L-selectin mRNA levels (p = 0.007) were significantly higher in the retinopathy group than in the no retinopathy group. Serum L-selectin levels were significantly higher (p = 0.04) in those with retinopathy compared to controls. Lymphocyte adhesion relative to control (100%) was essentially unchanged (84.0% (SD 27.7%), p = 0.15) for diabetic patients with no retinopathy and was markedly increased (192% (37.6%)) for those with retinopathy (p = 0.0001).


CONCLUSIONS
Lymphocyte activation, reduced surface L-selectin, increased circulating L-selectin, and a corresponding increase in adhesion of patients' cells using an in vitro assay, is evident in people with diabetic retinopathy. This suggests a role for lymphocyte activation in the pathogenesis of diabetic retinopathy.
Department of Ophthalmology, Raigmore Hospital, Inverness IV2 3UJ, Scotland, UK. janermackinnon@hotmail.com
J R
JR
MacKinnon
R M
RM
Knott
J V
JV
Forrester
D017252:CD3 Complex / Q000276:immunology; D002448:Cell Adhesion / Q000502:physiology; D003930:Diabetic Retinopathy / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology*; D004730:Endothelium, Vascular; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D019041:L-Selectin / Q000378:metabolism*; D008214:Lymphocytes / Q000097:blood / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008875:Middle Aged; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism
D017252:CD3 Complex; D008565:Membrane Proteins; D012333:RNA, Messenger; D019041:L-Selectin