The induction of hapten-specific immunological tolerance and immunity in B lymphocytes. VI. Differential tolerance susceptibility in adult spleen as a function of B-cell maturation level.

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Abstract
The maturation level of the B [bone marrow-derived] lymphocyte subpopulations involved in trinitrophenyl (TNP)-specific immunological tolerance in adult mice induced by the injection of trinitrobenzenesulfonic acid (TNBS) was investigated using in vitro antigen-specific and non-specific polyclonal stimulation. The maturity of the B cell subsets being studied was defined by the antigen or polyclonal activator which evoked a response. The thymic independent (TI-1) antigen TNP[Escherichia coli]-lipopolysaccharide (TNP-LPS) and the polyclonal stimulant LPS were used to activate immature neonatal-type B lymphocytes, whereas mature adult-type B cells were responsive to the TI-2 antigen, TNP-Ficoll and the non-specific activator [Mycobacterium tuberculosis] purified protein derivative (PPD). Whereas unresponsiveness in TNP-LPS-reactive (immature) B cells 4 d [days] after TNBS treatment was the result of functional deletion, partially reversible receptor blockade was detected early after tolerogen treatment. By the 24 h point, tolerance was irreversible as assessed by 24 h of antigen-free incubation and co-cultivation of tolerant cells with control splenocytes. Tolerance was induced more rapidly in immature TI-1 B cells than in mature TI-2 B lymphocytes. B lymphocytes reactive to TNP-Ficoll were less susceptible to receptor blockade. Using LPS as a non-specific probe for immature B cells, 60% tolerance in high affinity TNP-specific cells was induced within 12 h of TNBS treatment and complete unresponsiveness by 24 h. No significant decrease in response to the mature B cell activator PPD occurred until day 2. The 50% tolerance level was achieved in TNP-specific LPS-reactive B cells by 100 times less tolerogen than required for PPD-responsive cells. TNBS-induced unresponsiveness in cells reactive to TNP-LPS is initially a result of reversible receptor blockade which leads within 4 d to functional deletion. Immature, TI-1 B lymphocytes, which give polyclonal responses to LPS and antigen-specific responses to TNP-LPS, are rendered tolerant to TNBS more rapidly and at lower tolerogen doses than mature, TI-2 mouse B cells which react polyclonally to PPD and specifically to TNP-Ficoll. The immature and the mature B lymphocytes with these characteristic tolerance susceptibilities and specific and non-specific immune response patterns are present in the adult mouse spleen.