Reversal of B-cell immunization or tolerization by specific enzymatic degradation of antigen.

The mechanism of B-cell immunity or tolerance reversal by enzymatic treatment, was studied on cells stimulated in vitro by T-independent antigens, either sensitive or insensitive to enzymatic hydrolysis. B-cell stimulation induced by spleen cell incubation with DNP coupled to polymer was reversed when antigen-pulsed cells were treated with enzymes specifically hydrolytic for the carrier. Cell treatment with proteases abolished the response induced by DNP-POL (polymerized flagellin). Immunity or tolerance remained unchanged when induced by DNP conjugated to D-GL (D-glutamic and D-lysine copolymer) or to dextran B512 or B1299. While DNP-POL is a substrate for proteases, the latter three components are insensitive to the hydrolytic action of protease. B cells, preincubated with DNP-B512, were rescued from tolerance by dextranase treatment. Immunity and tolerance remained unchanged when induced by DNP-POL, DNP-B512 and DNP-B1299. While DNP-B512 was totally hydrolysed by dextranase, the latter three conjugates were not. These results show that (a) the initial stage for the induction of either immunity or tolerance is reversible, (b) the target of the enzymatic effect is the antigen itself, and (c) the interaction between polymeric antigen and B-cell Ig receptors is not sufficient to drive the cell to an irreversible stage of differentiation.