Requirement of the immunogen (E. coli β-galactosidase) for the response towards a determinant responsible for antibody-mediated enzyme activation, while antibodies binding some other sites can be elicited by mitogen alone
✍ Scribed by Enza Piccolella; Dora Centis; Franco Celada
- Publisher
- John Wiley and Sons
- Year
- 1981
- Tongue
- English
- Weight
- 497 KB
- Volume
- 11
- Category
- Article
- ISSN
- 0014-2980
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✦ Synopsis
Abstract
Virgin mouse spleen cells cultured in vitro without antigen or mitogen produce a measurable amount of IgM binding E. coli β‐galactosidase (β‐gal). Lipopolysaccharide (LPS) and LPS plus antigen enhance this response, which cannot be considered truly polyclonal since it does not include the production of antibodies directed towards a conformation‐dependent determinant, responsible for the activation of a mutant β‐gal, and known otherwise to be highly immunogenic. By priming in vivo with alum‐treated β‐gal (unable to elicit activating antibodies), an activating response is obtained in vitro by LPS plus antigen, but not by LPS alone.
These results are compatible with a two‐signal requirement for the activation of B cells and may be explained as follows: (a) the mitogen, in absence of immunogen, stimulates those clones which have a specific signal from cross‐reacting structures in the environment; (b) instead, no cross‐reactions are available for the conformation‐controlled structure of the „activating”︁ determinant; thus, intact immunogen is required as well as mitogen. Because of this „uniqueness”︁, the molecule of β‐gal offers a highly specific tool to probe carrier‐hapten relationships in native proteins.