CD40 LIGAND EXPRESSION ON THE SURFACE OF COLOSTRAL T-CELLS

The proportion of T lymphocytes, mainly CD4 positive, co-expressing th e CD40 ligand (CD40-L) was significantly greater (P=0.001) in the colo strum of 10 breast feeding mothers than in either autologous or hetero logous blood. This surface glycoprotein is a T cell molecule involved in B cell isotype switching and immunoglobulin production with its nat ural counter-receptor, CD40, expressed by both adult and infant B lymp hocytes. As the T cells of newborn infants fail to express the CD40-L when stimulated in vitro, the in vivo upregulation on milk T lymphocyt es may be one of the mechanisms through which the mother transfers imm une protection to the suckling infant.