Recombinant murine MALT lymphoma–derived antibodies are polyreactive. Three concentrations (0.1, 1, and 10 μg/mL) of 5 murine antibodies cloned from the tumors of 5 independent mice and recombinantly expressed in 293T cells were tested by ELISA for reactivity toward BSA, LPS, IgG, dsDNA, ssDNA, Escherichia coli, or Helicobacter felis sonicate and protein that was extracted from the mucosa of BALB/c stomachs (either infected with H felis or uninfected). Antibodies 2, 3, 8, and 11 display strong reactivity toward the majority of targets, whereas Ab10 has comparatively low affinity. A monoreactive antibody (mu AbGR1) was used as a control.