Comparative PCR of cDNAs generated from PB B-cell subsets of three donors. Shown are bands corresponding to V_κ-C_κ PCR products derived from the PB B-cell subsets of donors A to C and the bands corresponding to β-actin PCR-products derived from the respective subsets of donor B. IgM⁺IgD⁺, IgM⁺⁺IgD⁻, and IgG⁺ and IgA⁺ B-cell subsets and sample numbers of cDNA and PCR mixtures are indicated. Five thousand CE per cDNA mixture were amplified in separate reactions with V_κ-C_κ and β-actin primers.