The use of FITC‐conjugated gated monoclonal antibodies for determination of S‐phase cells with fluorescence microscopy

Abstract

A method is modified to determine the DNA synthesizing cells in primary human breast tumors and cells with idiopathic thrombocytopenic purpura (ITP) with FITC‐conjugated monoclonal antibody against bromodeoxyuridine (FITC‐M‐anti‐BrdUrd) and fluorescence microscopy. The DNA synthesizing cells were also determined from a portion of the same tissues by classical tritiated thymidine labeling (³HdThd) and autoradiography. The results from bromodeoxyuridine labeling index (BrdUrd‐LI) and tritiated thymidine labeling index (³HdThd‐LI) obtained from the same tissues were compared. The mean BrdUrd‐LI for breast tumor was 5.4 ± 1.0% and the mean ³HdThd‐LI was 5.5 ± 1.1%. Similarly, the labeling indexes obtained from mononuclear leukocytes of healthy donors had means of 0.5 ± 0.1% and 0.6 ± 0.1% for BrdUrd‐LI and ³HdThd‐LI, respectively. The change in the proliferation rate of mononuclear leukocyte population in the samples obtained from patients with ITP could be observed by both methods. The mean BrdUrd‐LI of mononuclear leukocytes for this hematological disorder was 5.4 ± 0.9% and the mean ³HdThd‐LI was 6.1 ± 0.8%. These results suggest that this relatively simple technique offers an alternative method for determining the DNA synthesizing cells in a given cell population.