Cytokeratins in normal epithelia

Most low molecular weight cytokeratins pair with a specific high molecular weight cytokeratin and most basic cytokeratins pair with an acidic cytokeratin3.

Epithelia may be classified as1:

  1. "simple": all non-stratified epithelia

  2. "stratified squamous": this includes cornifying and non-cornifying squamous epithelia

  3. "complex": all other stratified and pseudostratified epithelia.

All simple, ductal and pseudostratified epithelia express CK8 and CK183. Stratified epithelia loose their expression of CK8 and CK18: the "stratified keratins" comprise CK1 to CK6 and CK10 to CK17. CK5 and CK14/15 are expressed basally. The other isotypes are expressed suprabasally, as determined by the differentiation type. Cornification is associated with CK1/2 and CK10. The internal stratified squamous epithelia (tongue and oesophagus) express CK4 and CK13. Hyperproliferation (whether physiological or pathological) of cornified squamous stratified epithelium results in acquisition of CK63 and CK163.

Epithelium

basic (type II)

acidic (type I)

epidermis

13, (2), 5

103, 113, 14, (153)

Merkel cells of skin and taste buds of tongue

 

203

sole of foot

1, (2), 5, 6

9, 10, 11, 14, 16

anal canal

1, (2), 5, 6

10, 11, 13, 14, (15), (16), (17)

hair follicle (outer root sheath)

5, 6

14, (15), 16,17

sebaceous gland

4, 5, 6

(10), (11), 14, (15), (17)

cornea

33, 5

123

ectocervix

1, (2), 4, 5, 6

13, (14), (15), (16), (19)

tongue

4, 5, 6

13, 14, (15), 16, (17), (19)

epiglottis

4, 5, 6

13, 14, 15, 16, (17), (19)

oesophagus

4, 5, (6)

13, (14), (15), (16), (17), (19)

apocrine gland of axilla

4, 5, 7, 8

(13), 14, (17), (18), 19

eccrine gland

5, 6, 7, 8

14, 15, (17), 18, 19

mammary gland duct

5, 7, 8

14, (15), 17, (18), 19

trachea

5, (6), (7), 8

13, (14), 15, 17, (18), 19

amnion

5, 6, 8

(14), 17, (18), 19

urothelium

(4), 5, 7, 81

13, 17, 18, 19, 201

gallbladder

73,8

18,193

small intestine

8

18,19

colon

81

18,19,201,3

pancreatic acinar

7,81

18,191

mesothelium

7,81,3

183,191,3

lung alveoli

7,81

18,191

pancreatic ductal

81

18,191

hepatocytes

81

181

The characteristic cytokeratin profiles of the various normal epithelia tend to be retained following malignant transformation. However, caution is needed. The profiles are fundamentally a reflection of functional differentiation. Therefore, metaplastic cells express the cytokeratin profiles characteristic of their morphology and dedifferentiation can result in convergence of cytokeratin profiles1.

Cytokeratins are also expressed by mesenchymal cells, such as uterine and vascular smooth muscle, umbilical cord stroma, fetal myocardium and subserosal connective tissue2.

References

Novocastra catalogue 2001

1Southgate, J, Harnden, P., Trejdosiewicz, L. K. Cytokeratin expression patterns in normal and malignant urothelium: a review of the biological and diagnostic implications. Histol Histopathol 1999;14:657-664.

2Remotti, F., Fetsch, J. F., Miettinen, M. Keratin 1 expression in endothelia and mesenchymal tumors: an immunohistochemical analysis of normal and neoplastic tissues. Hum Pathol 2001;32:873-879.

3Chu, P. G. and L. M. Weiss (2002). "Keratin expression in human tissues and neoplasms." Histopathology 40(5): 403-39.

 

This page last revised 30.12.2003.

 

©SMUHT/PW Bishop