Splenic marginal zone lymphoma-like features in API2-MALT1 transgenic mice that are exposed to antigenic stimulation.

Recently, we described a transgenic mouse model to analyze the effect of the API2-MALT1 fusion-protein in vivo. Our results showed that the expression of API2-MALT1 is not sufficient to induce the development of lymphoma masses. Here, we demonstrate that immunization with Freund's complete adjuvant led to the loss of compartmentalization of the splenic white pulp in API2-MALT1 transgenic mice, resulting in a splenic marginal zone lymphoma-like lymphoid hyperplasia of a peculiar B-cell subset that disappeared as soon as the antigenic stimulation faded away. These data indicate an effect of API2-MALT1 expression on the normal immune response.