SERUM LEVELS, ONTOGENY AND HERITABILITY OF CHICKEN MANNAN-BINDING LECTIN (MBL)

Mannan-binding lectin (MBL) is a serum lectin found in mammals and rec ently also in birds. It is thought to play an important role in the in nate immune defence through binding to surface carbohydrates on micro- organisms followed by complement activation via the MBL pathway. This results in opsonization or direct complement-mediated killing. To gain further knowledge about the physiology and function of the protein, w e developed an enzyme-linked immunosorbent assay for chicken MBL and u sed this to investigate the level of MBL in different chicken strains during embryogenesis, early and adult life. The MBL concentrations in 308 chickens, representing 14 different strains, showed a non-Gaussian , unimodal distribution profile with a mean concentration of 5.8 mu g/ ml (range 0.4-37.8 mu g/ml). No difference between the strains could b e demonstrated and no chickens were found deficient in MEL. Ontogeneti c studies showed that MBL is already detectable in embryos at a gestat ional age of IO days (11 days before hatching). At hatching, the level is comparable to the level found in adult chickens. This level is fai rly stable during the first weeks of life, but a deficiency state deve lops at 4 weeks of age, whereafter the level is normalized again at 5 weeks of age. Chickens with relatively low or high MBL levels were bre d with cockerels having similar MBL levels and this resulted in F-1 ge nerations with significantly different MBL levels, suggesting that the protein level is genetically influenced.