Neutrophil gelatinase-associated lipocalin in normal and neoplastic human tissues. Cell type-specific pattern of expression

Neutrophil gelatinase-associated lipocalin (NGAL) has recently been identif ied in myeloperoxidase-negative neutrophil granules. Members of the lipocal in family are thought to bind and transport small lipophilic molecules such as retinoids and roles in cell regulation have been proposed. Recently, NG AL has also been demonstrated in the colonic mucosa in certain pathologic c onditions. The aim of this study was to examine the distribution of NGAL in normal and neoplastic tissues by immunohistochemistry. Interestingly, NGAL was found in a variety of normal and pathological human tissues. A cell type-specific pattern of expression was seen in bronchus, stomach, small intestine, panc reas, kidney, prostate gland, and thymus. The comparative analysis of the p utative rat homologue neu-related lipocalin showed a very similar pattern o f expression with the exception of pancreas and kidney. Neoplastic human ti ssues showed a very heterogeneous expression of NGAL protein. High NGAL lev els were found in adenocarcinomas of lung, colon and pancreas. In contrast, renal cell carcinomas of various subtypes and prostate cancers contained l ow NGAL levels. Lymphomas and thymic tumours were negative for NGAL immuno- labeling. Knowledge about the location of NGAL in normal cells and in disea se states provides the first clues towards understanding its biological fun ction.