KS1/4 antigen (Ag), defined by the KS1/4 antibody (KS1/4), is expressed in many epithelial-derived carcinomas and normal epithelial cell surfaces. The cDNA encoding KS1/4 has been isolated and contains an open reading frame of 314 amino acids including a putative signal sequence. KS1/4 Ag migrates as three glycosylated polypeptides with molecular masses of 35, 40 and 42 kDa. The 40 and 42 kDa species are similar proteins and appear to differ only by their degree of N-linked glycosylation. The 35 kDa species results from proteolytic cleavages of the larger molecular weight proteins. KS1/4 was first described as a monoclonal antibody which recognized a lung adenocarcinoma associated antigen. In oncolytic drug targeting studies, KS1/4 suppressed the growth of human lung tumor xenografts in athymic nude mice. Subsequent studies showed that KS1/4 reacts with a variety of tumor tissues including colon, breast, ovarian, and pancreas. It also recognizes normal epithelium including colon, stomach, small intestine, liver, kidney, lung, pancreas, skin and ovary. These results suggest that KS1/4 Ag represents an epithelial cell/epithelial-derived carcinoma marker. KS1/4 recognizes a 40 - 42 kDa antigen expressed on the cell surfaces of a variety of epithelial tumors and normal epithelial cell types. KS1/4 also recognizes a 35 kDa proteolytic fragment. UCLA-P3 cells derived from a human adenocarcinoma of the lung were used as immunogen.
The antibody was conjugated to BD Horizon™ BUV563 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 which has an Ex Max of 348 nm and an acceptor dye. The tandem has an Em Max at 563 nm. BD Horizon BUV563 can be excited by the 355 nm ultraviolet laser. On instruments with a 561 nm Yellow-Green laser, the recommended bandpass filter is 585/15 nm with a 535 nm long pass to minimize laser light leakage. When BD Horizon BUV563 is used with an instrument that does not have a 561 nm laser, a 560/40 nm filter with a 535 nm long pass may be more optimal. Due to the excitation and emission characteristics of the acceptor dye, there may be spillover into the PE and PE-CF594 detectors. However, the spillover can be corrected through compensation as with any other dye combination.