Recombinant human MALT lymphoma–derived antibodies are polyreactive. Three concentrations (0.1, 1, and 10 μg/mL) of 7 recombinant human MALT lymphoma antibodies (A) and 5 recombinant human CLL antibodies (B) were tested by ELISA for reactivity with the antigens indicated in the legends. All MALT lymphoma antibodies, with the exception of Ab2, but none of the CLL antibodies, exhibit a polyreactive binding pattern.