title: The role of eye-associated lymphoid tissue in corneal immune protection.
abstract: Because the cornea is optimized for refraction, it relies on supporting tissues for moistening and nutrition and in particular for immune protection. Its main support tissue is the conjunctiva, in addition to the lacrimal gland, the latter which provides soluble mediators via the tear film. The cornea and conjunctiva constitute a moist mucosal surface and there is increasing evidence that apart from innate defence mechanisms, also lymphoid cells contribute to the normal homeostasis of the corneal surface. A Medline-based literature search was performed in order to review the existing literature on the existence, composition and functions of mucosa-associated lymphoid tissue (MALT) at the ocular surface for corneal protection. The existence of lymphoid cells at the ocular surface and appendage has been known for many years, but for a long time they were believed erroneously to be inflammatory cells. More recent research has shown that in addition to the known presence of lymphoid cells in the lacrimal gland, they also form MALT in the conjunctiva as conjunctiva-associated lymphoid tissue (CALT) and in the lacrimal drainage system as lacrimal drainage-associated lymphoid tissue (LDALT). Together this constitutes an eye-associated lymphoid tissue (EALT), which is a new component of the mucosal immune system of the body. When the topographical distribution of CALT is projected onto the ocular surface, it overlies the cornea during eye closure and is hence in a suitable position to assist the corneal immune protection during blinking and overnight. It can detect corneal antigens and prime respective effector cells, or distribute protective factors as secretory IgA.
authors.affiliation: Research Laboratory of the Eye Clinic CVK, Charite - University School of Medicine, Berlin, Germany. erich.knop@charite.de
authors.forename: Erich
authors.initials: E
authors.lastname: Knop
authors.forename: Nadja
authors.initials: N
authors.lastname: Knop
mesh_terms: D003228:Conjunctiva / Q000033:anatomy & histology / Q000276:immunology; D003315:Cornea / Q000033:anatomy & histology / Q000276:immunology*; D005128:Eye Diseases / Q000276:immunology*; D006801:Humans; D018928:Immunity, Mucosal; D007765:Lacrimal Apparatus / Q000033:anatomy & histology / Q000276:immunology; D008221:Lymphoid Tissue / Q000033:anatomy & histology / Q000502:physiology*
references.citation: Lancet. 1998 Aug 8;352(9126):451-2
references.pmid: 9708756
references.citation: Dev Comp Immunol. 1998 Sep-Dec;22(5-6):621-30
references.pmid: 9877442
references.citation: Invest Ophthalmol Vis Sci. 1999 May;40(6):1266-70
references.pmid: 10235563
references.citation: Curr Eye Res. 1999 Sep;19(3):201-11
references.pmid: 10487957
references.citation: Exp Eye Res. 1999 Oct;69(4):397-403
references.pmid: 10504273
references.citation: Invest Ophthalmol Vis Sci. 1999 Oct;40(11):2506-12
references.pmid: 10509643
references.citation: Science. 1963 Nov 22;142(3595):1080-1
references.pmid: 14068229
references.citation: Immunol Today. 1999 Nov;20(11):505-10
references.pmid: 10529778
references.citation: Invest Ophthalmol Vis Sci. 2000 May;41(6):1270-9
references.pmid: 10798640
references.citation: Invest Ophthalmol Vis Sci. 2000 Sep;41(10):2922-9
references.pmid: 10967046
references.citation: Am J Ophthalmol. 1981 Jun;91(6):789-93
references.pmid: 7246703
references.citation: Ann Ophthalmol. 1981 Jan;13(1):61-3
references.pmid: 7247160
references.citation: Am J Ophthalmol. 1982 Aug;94(2):205-12
references.pmid: 7051834
references.citation: Ophthalmology. 1983 Jun;90(6):585-91
references.pmid: 6888852
references.citation: Br J Ophthalmol. 1983 Nov;67(11):737-41
references.pmid: 6639908
references.citation: Invest Ophthalmol Vis Sci. 1984 Feb;25(2):181-7
references.pmid: 6365826
references.citation: Cell Immunol. 1984 Jun;86(1):75-82
references.pmid: 6722896
references.citation: Exp Eye Res. 1985 Feb;40(2):231-8
references.pmid: 3884354
references.citation: Trans Ophthalmol Soc U K. 1985;104 ( Pt 4):363-6
references.pmid: 3862269
references.citation: Virchows Arch. 2000 Aug;437(2):185-9
references.pmid: 10993280
references.citation: Cornea. 2000 Sep;19(5):644-9
references.pmid: 11009316
references.citation: Prog Retin Eye Res. 2000 Nov;19(6):649-68
references.pmid: 11029550
references.citation: Arch Histol Cytol. 2000;63(5):431-9
references.pmid: 11201201
references.citation: Invest Ophthalmol Vis Sci. 2001 Mar;42(3):566-74
references.pmid: 11222512
references.citation: Nat Immunol. 2001 Dec;2(12):1093-4
references.pmid: 11725295
references.citation: Exp Eye Res. 2001 Oct;73(4):449-59
references.pmid: 11825017
references.citation: Biosci Rep. 2001 Aug;21(4):463-80
references.pmid: 11900322
references.citation: Cornea. 2002 May;21(4):405-9
references.pmid: 11973391
references.citation: Trends Immunol. 2002 Jul;23(7):333-5
references.pmid: 12103343
references.citation: Invest Ophthalmol Vis Sci. 2002 Aug;43(8):2609-14
references.pmid: 12147592
references.citation: Invest Ophthalmol Vis Sci. 2003 Feb;44(2):581-9
references.pmid: 12556386
references.citation: Adv Exp Med Biol. 2002;506(Pt A):539-45
references.pmid: 12613958
references.citation: Adv Exp Med Biol. 2002;506(Pt A):647-55
references.pmid: 12613973
references.citation: Adv Exp Med Biol. 2002;506(Pt B):835-44
references.pmid: 12614000
references.citation: Adv Exp Med Biol. 2002;506(Pt B):861-6
references.pmid: 12614003
references.citation: Adv Exp Med Biol. 2002;506(Pt B):867-72
references.pmid: 12614004
references.citation: Adv Exp Med Biol. 2002;506(Pt B):873-6
references.pmid: 12614005
references.citation: Ophthalmologe. 2003 Nov;100(11):929-42
references.pmid: 14669028
references.citation: Prog Retin Eye Res. 2004 Jan;23(1):1-30
references.pmid: 14766315
references.citation: Exp Eye Res. 2004 Mar;78(3):371-8
references.pmid: 15106915
references.citation: Am J Ophthalmol. 1966 Oct;62(4):672-6
references.pmid: 5929131
references.citation: Arch Ophthalmol. 1967 Mar;77(3):392-9
references.pmid: 6019562
references.citation: Acta Ophthalmol (Copenh). 1968;:Suppl 95:1+
references.pmid: 4170134
references.citation: J Exp Med. 1969 Feb 1;129(2):411-29
references.pmid: 4178353
references.citation: Albrecht Von Graefes Arch Klin Exp Ophthalmol. 1971;182(1):76-81
references.pmid: 4104912
references.citation: Am J Anat. 1973 Apr;136(4):455-77
references.pmid: 4692973
references.citation: Am J Ophthalmol. 1976 Apr;81(4):506-11
references.pmid: 1266931
references.citation: Am J Ophthalmol. 1976 Dec;82(6):819-26
references.pmid: 998699
references.citation: Am J Ophthalmol. 1978 Aug;86(2):250-9
references.pmid: 686127
references.citation: Adv Exp Med Biol. 1978;107:185-92
references.pmid: 742482
references.citation: Adv Exp Med Biol. 1978;107:53-9
references.pmid: 742502
references.citation: Int Ophthalmol Clin. 1979 Summer;19(2):93-109
references.pmid: 457353
references.citation: Invest Ophthalmol Vis Sci. 1979 Oct;18(10):1093-6
references.pmid: 478779
references.citation: Am J Ophthalmol. 1980 Mar;89(3):353-61
references.pmid: 6989250
references.citation: Invest Ophthalmol Vis Sci. 1981 Jan;20(1):100-9
references.pmid: 6161100
references.citation: Adv Exp Med Biol. 1998;438:643-51
references.pmid: 9634949
references.citation: Acta Ophthalmol Suppl. 1985;173:80-2
references.pmid: 3002113
references.citation: Trans Ophthalmol Soc U K. 1986;105 ( Pt 1):18-25
references.pmid: 3520980
references.citation: Ophthalmology. 1986 Oct;93(10):1276-83
references.pmid: 2947025
references.citation: Invest Ophthalmol Vis Sci. 1987 Mar;28(3):531-7
references.pmid: 3557866
references.citation: Ophthalmology. 1988 Jan;95(1):100-9
references.pmid: 3278257
references.citation: Acta Ophthalmol (Copenh). 1988 Feb;66(1):87-92
references.pmid: 3284275
references.citation: Vet Pathol. 1989 May;26(3):222-30
references.pmid: 2763412
references.citation: Vet Pathol. 1991 Jan;28(1):22-9
references.pmid: 2017824
references.citation: Am J Vet Res. 1991 Nov;52(11):1852-9
references.pmid: 1785728
references.citation: Physiol Rev. 1992 Oct;72(4):853-79
references.pmid: 1438580
references.citation: Curr Eye Res. 1994 Jan;13(1):87-93
references.pmid: 7908866
references.citation: J Pathol. 1994 Sep;174(1):33-7
references.pmid: 7965401
references.citation: Anat Rec. 1995 Oct;243(2):153-64
references.pmid: 8554171
references.citation: Arch Histol Cytol. 1995 Dec;58(5):517-22
references.pmid: 8845233
references.citation: Invest Ophthalmol Vis Sci. 1997 Apr;38(5):884-92
references.pmid: 9112984
references.citation: Exp Eye Res. 1997 Jun;64(6):905-12
references.pmid: 9301471
references.citation: Surv Ophthalmol. 1997 Nov-Dec;42(3):233-46
references.pmid: 9406369
references.citation: Adv Exp Med Biol. 1998;438:461-9
references.pmid: 9634922
references.citation: Adv Exp Med Biol. 1998;438:557-65
references.pmid: 9634937