Immunoreactive Score
The immunoreactive score (IRS) is a rating scale used to quantify progesterone and estrogen receptors on the surface of tumor cells. The score is therefore used to classify breast tumors in immunohistochemistry (immunohistochemical hormone receptor detection).
Tissue removed is fixed and prepared for immunostaining and then incubated with POD- labeled antibodies against the respective receptors. After the color reaction has taken place, the presence of the receptors on the cell surface can be recognized by the color. The values for the score are obtained after evaluating and counting the colored cells ( IS = staining intensity, dt. Color intensity ) multiplied by the proportion of positive cells ( PP = percentage points, dt. Percentage points ).
| Staining intensity | Positive cells | ||
|---|---|---|---|
| 0 | no reaction | 0 | no |
| 1 | weak response | 1 | less than 10% |
| 2 | moderate response | 2 | between 10 and 50% |
| 3 | strong reaction | 3 | between 51 and 80% |
| 4th | more than 80% | ||
| IRS | |
|---|---|
| 0-2 | negative |
| 3-4 | weak positive |
| 6-8 | moderately positive |
| 9-12 | strongly positive |
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- Lothar Thomas: Laboratory and Diagnosis . 6th edition. Frankfurt 2005, pp. 1359 f., ISBN 3-9805215-5-9