Tips for the storage of antibodies
A. Storage of lyophilized antibodies:
1. Unlabeled antibodies are stable without loss of quality at ambient temperatures for several weeks or even a few months. They can be stored at 4°C for several years.
2. Fluorescence-labeled antibodies should be reconstituted upon delivery.
B. Storage of antibodies supplied as a liquid:
After reconstitution, storage conditions depend on the type of antibody.
1. Monoclonal antibodies
When ascites grade antibodies are reconstituted, typically small amounts of azide are added to prevent microbial growth. Ascites should be stored frozen. Monoclonal antibodies usually do not suffer from repetitive freeze-thawing but you may aliquot them into small samples to avoid too many freeze-thaw cycles. Prolonged storage at 4°C is not recommended! Unlike serum, ascites may contain proteases that will ultimately degrade the antibodies. Addition of protease inhibitors helps to slow degradation.
b. Hybridoma supernatant should be stored in the same manner as ascites.
c. Purified Monoclonal antibodies
Do not store diluted antibody solutions unless you add detergent or carrier proteins such as goat serum, BSA or other carriers. IgG sticks to glass and plastic. Any IgG solution below 0.1 mg/ml protein will quickly adsorb and denature and thus lose activity! Repetitive freeze-thawing of dilute purified IgG is almost certain to lead to substantial losses.
2. Polyclonal antibodies
a. Rabbit antisera
Antisera are more robust than monoclonal antibodies. With anti-microbials added, they may be stored at 4°C. Serum does not contain active proteases, in fact, serum itself contains a powerful cocktail of protease inhibitors. Frozen storage is preferable.
b. Polyclonal affinity purified antibodies
Affinity purified antibodies are less robust than sera, since protease inhibitors are also removed during purification. Hence, storage at 4°C for prolonged periods is not recommended.