Mechanism of b-lymphocyte activation: failure to obtain evidence of a direct role of the Ig receptors in the triggering process
Abstract
Experiments were designed to test two hypotheses of B-cell activation by antigen: the cross-linking concept, postulating that a suitable degree of antigen-induced cross-linking of the Ig receptors is sufficient for immunocyte triggering, and the two-signal hypothesis, suggesting that a first signal delivered by antigen interacting with the Ig receptors followed by a second signal given by, for example, a polyclonal B-cell activator is necessary for activation. The results did not support either of these hypotheses. Thus, the hapten FITC coupled to human serum albumin and human gammaglobulin in different conjugation ratios failed to activate B cells, whether the hapten-protein conjugates were soluble or precipitated, whether the experiments were carried out in the presence or absence of different concentrations of sera from different species, and irrespective of the day of assay. Furthermore, the same FITC-protein conjugates or FITC itself coupled to Sepharose particles failed to induce a specific anti-FITC response, even though a range of 10-9-fold concentrations of FITC were used. In contrast, FITC coupled to lipopolysaccharide (LPS) regularly induced a primary anti-FITC response in all the above systems, whether FITC-LPS was ...Continue Reading
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B cell Activation
B cell activation is initiated by the ligation of the B cell receptor with antigen and ultimately results in the production of protective antibodies against potentially pathogenic invaders. Here is the latest research.