Washing Buffer: Ideally, washing will break all nonspecific interactions while preserving the specific interaction between antibody and antigen (and antigen and binding partners for co-IP). Washing with additional Lysis Buffer is common, as it typically contains mild denaturants that can help break nonspecific interactions. If background is a problem, increasing the stringency of the wash buffer may help obtain a more purified antigen and antigen-binding partners from the sample.