Interest has recently been shown in adapting the microwave oven heating technique for antigen retrieval to routine diagnostic immunocytochemical practice. Although it has proved effective as a specialist method for individual antigen localization in many laboratories, it has certain drawbacks which have hampered its wider routine application. These include the need to monitor the sections during the microwave treatment to prevent damage or drying, the limited number of sections that can be accommodated in the microwave oven, and the inevitable alteration in nuclear morphology induced by the microwaves. In order to obviate these difficulties, we have modified the wet autoclave method of Shin et al. (Lab Invest 1991; 64: 693-702) as a routine technique for retrieval of a variety of cell surface, cytoplasmic, and nuclear antigens in formalin-fixed and paraffin-embedded tissue. The technique produces even enhancement of several refractory antigens in anatomically different sites and has the potential to handle reliably up to 200 sections at a time without significant damage to the section or to nuclear morphology.

Metallothioneins (MTs) are ubiquitous low-molecular-weight proteins with a high affinity for heavy metal ions such as zinc, copper and cadmium. MT over-expression has been associated with resistance against anticancer drugs. In the present study we investigated 86 cases (45 cases of tumour category pT1 and 41 of category pT2) of routinely fixed and paraffin-embedded primary breast carcinomas immunohistochemically with a monoclonal antibody to an epitope of MT shared by its I and II isoforms. Immunohistochemically demonstrated MT over-expression was found in the invasive components of 7 of 32 pT1 and 17 of 28 pT2 invasive ductal carcinomas, whereas all 26 invasive lobular carcinomas gave weak or negative results. Fourteen of 17 pT2 and 2 of 7 pT1 invasive ductal carcinomas with MT over-expression developed metastases during follow-up with poor prognostic outcome. In contrast only 3 of 11 pT2 and none of the 25 pT1 cases without MT over-expression had a poor clinical course (P < 0.001). It is concluded that MT over-expression is associated with significantly poor prognosis particularly in pT2 invasive ductal breast carcinomas.

The distribution of simple epithelial (K8/18/19) and basal (myoepithelial) (K5/14) keratins, alpha-smooth-muscle actin, vimentin, collagen IV and laminin in normal mammary glands and in benign proliferative lesions was studied using monoclonal antibodies (mAbs). These antibodies (Abs) identified myoepithelial cells and luminal cells specifically. In lesions with adenosis and papillomas, the two-layered formation resembled that of normal glands with a purely myoepithelial-epithelial differentiation. In scleradenotic lesions, the main cell was of myoepithelial immunophenotype with intermixed trabecular-tubular proliferations of simple-type epithelium. The sclerosis seems to be the result of an irregular basal lamina synthesis by the myoepithelial cells. In contrast to these lesions, epitheliosis represents a purely intraluminal cell proliferation of clearly simple epithelial immunophenotype and of cells with a basal keratin phenotype, lacking myoepithelial differentiation antigen actin. The basal keratin type epithelium may represent post-stem or intermediate cells developing into luminal epithelium. Epitheliosis appears to be a purely epithelial hyperplasia with striking similarity to the regeneration of normal breast epithelium. The different proliferative patterns may give an explanation for differences in potential cancer risks of patients with these lesions.

Qualitative and quantitative changes of CD44 expression are implicated in early stages of breast carcinogenesis. The restricted neo-expression of certain CD44 isoforms in breast neoplasias suggests that CD44 might be a potential target for future antibody-based tumour therapy.

No abstract