Immunoglobulin A protects the bodys
mucosal surfaces from infection and in secretions, it is found as a dimer (400 kD) joined by a short J chain and linked to a secretory portion or transport piece. In
serum found as a monomer (170 kD).
Immunoglobulin A is the main mechanism for providing
local immunity against infections in the gut or respiratory tract and may act by reducing the binding between an
immunoglobulin A coated micro organism and a host
epithelial cell. Present in human
colostrum but not transferred across the
placenta. Have heavy chains.
source: online medical dictionary: http://www.graylab.ac.uk/