Igκ and Igγ expression in cancers, benign lesions and normal tissues of breast by immunohistochemistry.

<p>A: Igγ (a1, a3) and Igκ (a2, a4) are diffusely positive in cell cords and single cell chains in IDC (a1 and a2) and ILC (a3 and a4) (arrowheads) with stronger staining in B lymphocytes/plasma cells (letterheads) in stroma. B: Igγ (b1) and Igκ (b2) are expressed in some cells inside large cell groups of IDC (arrowheads) and infiltrating lymphocytes (letterheads). In DCIS Igγ (b3) and Igκ (b4) expression can be seen in a few cells (arrowheads). C: Igκ positive cells can also be seen in glandular epithelial cells (arrowheads) of fibroadenoma (c1) along lumens and in a limited number of fibroblasts (letterhead) in the interstitium. Igκ expression can seldom been detected in normal breast duct adjacent to benign breast lesion (cystic hyperplasia of breast) (c2). Destain & restain with antibodies to Igκ and CD20 on IDC shows more Igκ expression in infiltrating cancer cells (c3, letterheads) than in adjacent histologically normal breast duct (c3, arrowhead), with infiltrating B lymphocytes as internal positive control (costaining with both Igκ and CD20) (c4, black arrow). D: By conducting immonostaining and destain & restaining with antibodies against Igγ, Igκ, CD20 and CK on two consecutive sections of axillary lymph node metastatic breast cancer tissue, we observed costaining of Igγ and Igκ in both breast cancer cells (d1 and d2) in cancer nest (CK positive) and stronger staining in B lymphoid/plasma cells (d1 and d2, letterheads) in tumor stroma. The lymphoid/plasma cells with or without CD20 staining (d3, letterhead) in tumor stroma showed no positive CK staining with breast cancer cells as internal positive control (d4, arrowheads). Original magnifications: a1–a4, b1 and b2 ×200, scale bars: 40 µm; others ×400, scale bars: 20 µm.