Assessment Run 5 2001 

Ki-67

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The slides to be stained for Ki67 contained three follicular lymphomas.

42 laboratories submitted the staining. 30 laboratories used mAb MIB-1, 9 used Dako's pAb, 1 used KiS5, 1 used MM1, and 1 used a non-specified Ventana Ab.

At the assessment optimal staining was achieved in 15, acceptable in 15, borderline in 7 and poor staining in 5 of the laboratories. Optimal staining was only seen, when mAb MIB-1 was used and an efficient HIER was performed.

The main reasons for a borderline or poor staining was insufficient heat induced epitope retrieval and a too dilute primary antibody compared to the overall sensitivity of the protocol.

Representative fields are illustrated below (Fig. 1). Two examples of protocols giving optimal stainings are linked.

Fig. 1A. Optimal staining, using MIB-1. In all three lymphomas, intense staining of nuclear Ki-67 is seen in a proportion of tumour cells.

Good protocol-1  Good protocol-2
Fig 1B (same fields as in Fig. 1A, same Ab). Borderline staining. In the tumours to the left and in the middle, fewer nuclei are stained. In the right tumour, no nuclear staining is seen. The main reason for the suboptimal result in this case was insufficient HIER in combination with a too dilute antibody.

Fig 1C (same fields as in Fig. 1A, same Ab). Poor staining. In the left tumour there are fewer nuclei stained than in Fig. 1B, while the two other tumours show no staining.

MV/SN

Last update: 01-04-07