B-cell repopulation of adult SCID mice with embryo cell lines and induction of specific humoral immune responses.

(A) Serum IgM^a levels of reconstituted mice at 1 and 2 months after the adoptive transfer of embryo cell lines. They were defined by comparison to normal BALB/c serum levels (10⁰titer). The data were obtained in IgM allotype-specific ELISAs as described in “Materials and methods.” Each point corresponds to one independent mouse. The mean values are indicated as in Figure 4. (B) Sequential anti-DNP IgM^a serum titers were calculated with DNP-specific ELISAs after immunization with DNP-LPS. Black circles and triangles correspond to the mean values of 3 recipient SCID mice, each one injected with a different embryo cell line. Empty circles show the serum anti-DNP IgM^a+ titers of reconstituted, but unimmunized, SCID mice (upper histogram). Empty squares and triangles are the mean values of 3 BALB/c and BALB/c^nu/nu mice, respectively (lower histograms).