Figure 5. Long-term colonization of the BM by IgM-secreting PCs.

(A) BM PC subsets were sorted and assayed at the indicated time points post-immunization with NP-CγG as described in Figure 3A using ELISPOT plates coated with either NP₂₆-BSA or NP₄-BSA. These plates were probed subsequently with anti-μ chain or anti-γ chain antibodies, respectively. *, p<0.01. (B) Separate experiment wherein sorted BM PC subsets were assayed by ELISPOT at the indicated time points post-immunization using NP₄-BSA-coated plates and anti-γ chain antibodies. *, p<0.01. (C) Additional experiment wherein the indicated BM PC subsets were sorted and assayed for secretion of NP-specific antibodies at the indicated time points using NP₂₆-BSA-coated plates and anti-κ or anti-λ antibodies. Numbers of hapten-specific PCs in the BM at each time point were calculated as described in Methods. *, p<0.01.