Paper Information

Journal:   ACTA MEDICA IRANICA   2003 , Volume 41 , Number 2; Page(s) 73 To 78.
 
Paper: 

INDUCTION OF THYMIC HLA-DR SIGNALING WITH ALPHASMOOTH MUSCLE ACTIN EXPRESSION DURING THE SECOND AND THIRD TRIMESTERS OF GESTATION

 
 
Author(s):  TAMIOLAKIS D., VENIZELOS J., KOTINI A., SKAFIDA P., CHEVA A., PAPADOPOULOS N.
 
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Abstract: 
Less than 5% of prenatal thymocytes express HLA-DR before week 12 of gestation. However, the number of HLADR-positive cells increases during the late second and third trimesters of development. To determine the role of alpha-smooth muscle actin in fetal thymic HLA-DR signaling in different stages of development we examined and compared the immunohistochemical expression of alpha-smooth muscle actin in the myoid cells of the thymic medulla stroma in the 2nd, and 3rd trimesters of gestation respectively, over the equivalent expression of the protein in the 1st trimester, in relation with the appearance of HLA-DR-positive thymocytes. Our results demonstrated a quantitative difference in the second and third trimesters of development concerning the expression of alpha-smooth muscle actin in the stromal myoid cells of the thymic medulla over the equivalent expression of the protein in the first (p<0.0001, t-test). Similar changes in the above period were found concerning the expression of HLA-DR over the first (p<0.0001, t-test), suggesting a direct involvement of alpha-smooth muscle actin in the sustainence of HLA-DR reactivity. Our data provide evidence that a contractile microfilament alpha-smooth muscle actin plays a pivotal role in HLA-DR expression, through interaction between medullary stromal cells and thymocytes.
 
Keyword(s): MEDULLARY THYMOCYTES, HLA-DR SIGNALING, ALPHA-SMOOTH MUSCLE ACTIN, MYOID CELLS, 2ND AND 3RD TRIMESTERS OF GESTATION.
 
References: 
 
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