Abstract
The immune response of BALB/c mice to phosphorylcholine (PC) is dominated by an antibody bearing the idiotype of the myeloma protein TEPC 15 (MP T15). Anti‐PC antibody of a different idiotype can be elicited in BALB/c mice by neonatal suppression with an anti‐T15 idiotypic antiserum (anti‐Id‐T15).
In an attempt to further characterize the immune response to PC, spleen cells of normal and idiotypically suppressed mice have been fused with the myeloma line X63‐Ag8, and hybrid lines secreting anti‐PC antibodies have been isolated. The antibodies were characterized by two‐dimensional gel electrophoresis and their affinity for Pneumococcus pneumoniae was measured. Using both an A/J and a rabbit anti‐Id‐T15 serum, we could show that 4 out of 5 hybridomas obtained from normal BALB/c spleen cells secreted antibodies which, within the limits of the analysis, were idiotypically and structurally indistinguishable from MP T15 (T15^+^). Hybridomas obtained from suppressed BALB/c mice, on the other hand, secreted anti‐PC antibodies which differed idiotypically from MP T 15: of the six lines, two were negative for T15 idiotopes (T15^−^), while four showed some cross‐reactivity with the T15 idiotype (T15^cr^). All six, however, showed structural differences in one or more immunoglobulin chains.
Inhibition of anti‐PC plaque‐forming cells induced in neonatally suppressed mice revealed that the idiotypic spectrum of the hybridoma proteins was representative of clones arising under such conditions in BALB/c mice. The majority of the anti‐PC antibodies in idiotypically suppressed mice still bear idiotopes resembling MP T15. Only a minority, less than 20%, are truly T15^−^.