The B and T regions in 495 axillary lymph nodes (TU-LN) draining 104 invasive breast carcinomas and 34 non-tumor-draining axillary/cervical lymph nodes (R-LN) were investigated immunohistochernically in frozen sections. The extents of the B regions and T regions were evaluated by staining with TO15 (CD22) and Leu-1 (CD5), respectively. Staining with Ki-M4, which specifically recognizes follicular dendritic cells, enabled determination of the number of lymphatic follicles. The germinal-center index (GCI), the numerical ratio of primary to secondary follicles, was determined to quantify the reactivity of the B regions. The number of Ki-67+ proliferating lymphoid cells per 0.5 mm(2) T region (PCT) was assessed as an index of the reactivity of the T regions. (i) In the TU-LN, the median GCI and PCT (0.1 and 18, respectively) were significantly lower than in the R-LN (0.6 and 26, respectively; both p<0.01). (ii) Greater TU-LN volumes were found to be associated with predominance of the T regions, high GCIs, and high PCTs. (iii) Higher GCIs and PCTs were associated with predominance of the T regions in TU-LN in general, but TU-LN partially destroyed by tumor metastases exhibited higher GCIs and PCTs when there was predominance of the B regions. The findings of the study show that LN draining breast carcinomas and reactive LN with signs of chronic nonspecific lymphadenitis exhibit significant immunohistochemical differences but it remains open to speculation whether the malignant tumor exerts suppressive effects on the lymphoreticular tissue or whether its antigenicity is low, particularly when compared with common, mostly infectious stimuli leading to chronic lymphadenitis.

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