While the immune microenvironment has been investigated in breast cancers, little is known about its role in non-malignant breast tissues. Here we quantify and localize cellular immune components in normal breast tissue lobules, with and without visible immune infiltrates (lobulitis). Up to ten representative lobules each in eleven normal breast tissue samples were assessed for B cells (CD20), cytotoxic T cells (CD8), helper T cells (CD4), dendritic cells (CD11c), leukocytes (CD45), and monocytes/macrophages (CD68). Using digital image analysis, immune cell densities were measured and compared between lobules with/without lobulitis. 109 lobules in 11 normal breast tissue samples were evaluated; 31 with lobulitis and 78 without. Immune cells showed consistent patterns in all normal samples, predominantly localized to lobules rather than stroma. Regardless of lobulitis status, most lobules demonstrated CD8+, CD11c+, CD45+, and CD68+ cells, with lower densities of CD4+ and CD20+ cells. Both CD11c+ and CD8+ cells were consistently and intimately associated with the basal aspect of lobule epithelium. Significantly higher densities of CD4+, CD8+, CD20+, and CD45+ cells were observed in lobules with lobulitis. In contrast, densities of monocytes/macrophages and dendritic cells did not vary with lobulitis. In normal breast tissue, myeloid and lymphoid cells are present and localized to lobules, with cytotoxic T and dendritic cells directly integrated with epithelium. Lobules with lobulitis have significantly more adaptive immune (B and T) cells, but no increase in dendritic cells or monocytes/macrophages. These findings indicate an active and dynamic mucosal immune system in normal breast tissue.

In breast adipose tissue, macrophages that encircle damaged adipocytes form "crown-like structures of breast" (CLS-B). Although CLS-B have been associated with breast cancer, their role in benign breast disease (BBD) and early carcinogenesis is not understood. We evaluated breast biopsies from three age-matched groups ( = 86 each, mean age 55 years), including normal tissue donors of the Susan G. Komen for the Cure Tissue Bank (KTB), and subjects in the Mayo Clinic Benign Breast Disease Cohort who developed cancer (BBD cases) or did not develop cancer (BBD controls, median follow-up 14 years). Biopsies were classified into histologic categories, and CD68-immunostained tissue sections were evaluated for the frequency and density of CLS-B. Our data demonstrate that CLS-B are associated with BBD: CLS-B-positive samples were significantly less frequent among KTB biopsies (3/86, 3.5%) than BBD controls (16/86 = 18.6%, = 0.01) and BBD cases (21/86 = 24%, = 0.002). CLS-B were strongly associated with body mass index (BMI); BMI < 25: 7% CLS-B positive, BMI 25-29: 13%, and BMI ≥ 30: 29% ( = 0.0005). Among BBD biopsies, a high CLS-B count [>5 CLS-B/sample: 10.5% (BBD cases) vs 4.7% (BBD controls), = 0.007] conferred a breast cancer OR of 6.8 (95% CI, 1.4-32.4), = 0.02, after adjusting for adipose tissue area (cm), histologic impression, and BMI. As high CLS-B densities are independently associated with an increased breast cancer risk, they may be a promising histologic marker of breast cancer risk in BBD. .

Little is known about the role of the immune system in the earliest stages of breast carcinogenesis. We studied quantitative differences in immune cell types between breast tissues from normal donors and those from women with benign breast disease (BBD). A breast tissue matched case-control study was created from donors to the Susan G. Komen for the Cure Tissue Bank (KTB) and from women diagnosed with BBD at Mayo Clinic (Rochester, MN) who either subsequently developed cancer (BBD cases) or remained cancer-free (BBD controls). Serial tissue sections underwent immunostaining and digital quantification of cell number per mm for CD4 T cells, CD8 T cells, CD20 B cells, and CD68 macrophages and quantification of positive pixel measure for CD11c (dendritic cells). In 94 age-matched triplets, BBD lobules showed greater densities of CD8 T cells, CD11c dendritic cells, CD20 B cells, and CD68 macrophages compared with KTB normals. Relative to BBD controls, BBD cases had lower CD20 cell density ( = 0.04). Nearly 42% of BBD cases had no CD20 B cells in evaluated lobules compared with 28% of BBD controls ( = 0.02). The absence of CD20 cells versus the presence in all lobules showed an adjusted OR of 5.7 (95% confidence interval, 1.4-23.1) for subsequent breast cancer risk. Elevated infiltration of both innate and adaptive immune effectors in BBD tissues suggests an immunogenic microenvironment. The reduced B-cell infiltration in women with later breast cancer suggests a role for B cells in preventing disease progression and as a possible biomarker for breast cancer risk. .

Our classification method provides further clarity and systematic standardization for reporting TT complications.

ADH on core biopsy with low risk of upgrade to cancer is defined by lack of individual cell necrosis, number of foci of ADH, and percent of imaging lesion removed. If these findings are validated, women whose biopsies meet low-risk criteria might be considered for prevention therapy and surveillance without surgical excision.