Primer for the isotype-specific amplification of the complete variable regions.

One universal forward primer was used for annealing within the leader region. For each isotype, a reverse primer was generated for specific amplification. The annealing sites were selected in the first constant region (IGCH1), with the exception of IgM and IgD. Both isotypes share high homologies in the IGCH1 and therefore, specific reverse primers were generated for binding in the second constant region. The IgG subtypes were not distinguished further. Primers for bovine GAPDH served as cDNA quality control.