This is a single-arm, open-label study of Iodine 131 Anti B1 Antibody for the treatment of 1st or 2nd relapsed indolent B cell lymphomas or B cell lymphomas that have transformed to a more aggressive histology. The primary endpoint of the study is to determine the response rate. Secondary endpoints of the study is to determine the duration of response, time to progression, time-to-treatment failure, safety, and survival.