Camelid immunoglobulins and their importance for the new-born - A review

Camelid immunoglobulins differ from all other known antibodies and contradi ct all common theories on antibody diversity. It was demonstrated that up t o 75% of all serum proteins are immunoglobulin G (IgG) molecules lacking li ght chains. IgG(2) and IgG(3), which only consist of heavy chains, have a l ow molecular weight which improves their biodistribution and allows a bette r tissue penetration. Of special importance is the long complementary deter mining region (CDR) loop which inserts deep into the active site of an enzy me. This binding property was only observed in experiments to gain structur al data and to point out the extraordinary value of heavy chain antibodies as biochemical and pharmacological tools. The acquisition and absorption of adequate amounts of colostral immunoglobulins are essential to the health of the neonate, Pre-colostrum serum IgG levels in camelids are low, with co ncentrations of 0.26 +/- 0.23 mg/ml. Maximum IgG levels are reached after 2 4 h and kept at a plateau with concentrations of 24.52 +/- 8.8 mg/dl. IgG c oncentrations above 10 mg/ml. indicate a successful passive transfer. IgG l evels decline after 2-5 weeks and a marked increase is observed between 1 a nd 2 months, indicating that the immune system of the neonate has started t o mature. A number of different tests are available for the assessment of I gG serum levels. Single radial immunodiffusion (SRID) is the only method th at specifically measures serum IgG concentrations. It is a reliable assay t o test failure of passive transfer (FPT). FPT is a major factor in neonatal mortality in camelids, but very little has been published so far. Therapeu tic administration of colostrum will provide passive protection against inf ectious diseases for a 2-3-week period of risk, and the intravenous adminis tration of 20-40 ml of camelid plasma helps to combat FPT.