METHODS IN PATHOLOGY - IMMUNOCYTOCHEMICAL DETECTION OF CYCLIN-A AND CYCLIN-D IN FORMALIN-FIXED, PARAFFIN-EMBEDDED TISSUES - NOVEL, PERTINENT MARKERS OF CELL-PROLIFERATION

Cyclin proteins in association with cyclin-dependent protein kinase su bunits represent a new class of potentially oncogenic serine/threonine protein kinases that function to execute critical cell cycle transiti ons in all eukaryotic cells. Characterized by dramatic fluctuations in abundance, which occur in accordance with the periodicity of the cell cycle, the expression patterns of specific cyclins provide a unique a nd relevant indicator of cellular activation and cell cycle progressio n. In this study, we introduce a series of monospecific antibodies tha t are selective for human cyclin A and cyclin D, respectively, and we assess the feasibility of utilizing these reagents for immunocytochemi cal analyses. Conditions were optimized for detecting cyclin A and cyc lin D in formalin-fixed, paraffin-embedded sections of the postnatal h uman palatine tonsil, in which normal cell proliferation is well chara cterized. Subsequent studies demonstrated the performance of these ant ibodies in the examination of pediatric bone tumors, in which decalcif ication methods are additionally performed. In both cases, the prolife rative status of individual cells was monitored with an exceedingly hi gh degree of resolution. Taken together with the available biochemical data, the results of these studies reveal a novel means of characteri zing the proliferative status of normal as well as neoplastic tissues. The demonstrated utility of these immunochemical reagents will potent ially facilitate retrospective studies aimed at examining cell prolife ration in a wide variety of archival histopathologic specimens.