Cd22^tm1Tft

A PGK-neo cassette replaced a portion of the 5' untranslated region, the leader sequence, and a portion of the exon encoding the immunoglobulin (Ig) 1 domain. A stop codon was introduced into the 5' end of the exon encoding the Ig 1 domain. Immunohistochemical staining of frozen spleen sections, using various Ig-specific antibodies, showed a lack of secreted, cell surface, and cytoplasmic protein. The absence of sell surface expression was further confirmed by immunofluorescence staining of lymphocytes. (J:38051)