As a part of our quality assurance program, all antibodies and cell lines undergo a strict screening/validation procedure before delivery.

Monoclonals

For a monoclonal project, each candidate antibody is tested against its respective antigen in an ELISA assay.  Only those with a titer greater than 100,000 (corresponding to nanomolar affinity) are chosen for further screening.  Each candidate cell line is subject to 2-3 rounds of subcloning.  Only those retaining 100% positive clone rate and a sufficient level of IgG secretion are sent to customers.

Polyclonals

For a polyclonal project, antibodies are purified on an affinity column containing the antigen.  All non-specific antibodies are thus removed.

Modification-Specific Polyclonals

Frequently, our customer would need highly specific antibodies for a modified (e.g., phosphorylated, acetylated or methylated) protein.  In this case, we would synthesize two peptides:

an antigen peptide with the modification: XXXXXXMXXXXXX (M=modified residue)
and a control peptide without the modification: XXXXXXAXXXXXX (A=unmodified residue)

We would first immunize rabbits with the antigen peptide and harvest polyclonals.  The antibodies then go through two affinity columns: the first one contains the antigen peptide.  Therefore, all antibodies binding to the modified protein are collected on this column.  The captured antibodies are then passed through a column with the control peptide.  In this step, non-specific antibodies (i.e., those binding both the modified and unmodified protein) are removed.