ANTIGEN-SPECIFIC EARLY PRIMARY HUMORAL RESPONSES MODULATE IMMUNODOMINANCE OF B-CELL EPITOPES

Accumulation of primary Abs against two distinct epitopes on a designe d polypeptide, MEP-1, was examined. The early primary response was pre dominantly against a C-terminal epitope (MEP 77-100), although subsequ ent maturation established an epitope within the N-terminal half (MEP 17-31) as the immunodominant one. Inversion of immunodominance correla ted with the inability of anti-MEP 77-100 B cells to interact producti vely with T cells, which consequently received reduced help. Interacti on between epitope-specific B and T cells was found to be attenuated i n the presence of early primary anti-MEP-1 antiserum, and the extent o f inhibition was directly proportional to the level and affinity of ep itope-specific Igs. Therefore, it seems that early primary Abs to a mu ltideterminant Ag selectively down-regulate maturation of epitope-spec ific primary humoral responses.