DETECTION OF PIP-GCDFP-15 GENE-EXPRESSION IN APOCRINE EPITHELIUM OF THE BREAST AND SALIVARY-GLANDS

Gross cystic disease fluid protein-15 (GCDFP-15) is a protein characte ristic of apocrine epithelium. Its amino acid sequence is identical to that of prolactin-inducible protein (PIP), whose gene has been locali zed on the long arm of chromosome 7. We have developed an in situ hybr idization (ISH) procedure using a digoxigenin-labeled riboprobe to det ect PIP-specific mRNA. The immunocytochemical results obtained with an ti-GCDFP-15 antiserum were compared on parallel sections with those ob tained by ISH using the PIP riboprobes on a variety of formalin-fixed, paraffin-embedded tissues. Similarities and differences of staining p atterns obtained with both methods were described and discussed. These included positivity with both methods of apocrine epithelium of the b reast and serous acinar glands of salivary and bronchial tissues. Macr ophages and luminal content in the breast were positive with the immun ological method and negative with ISH. Immunohistochemistry stained th e luminal pole of the cell whereas perinuclear staining was obtained w ith ISH.