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[[File:Dendritic cells.jpg|thumb|300px|Section of [[skin ]] showing large numbers of dendritic cells (Langerhans cells) in the [[Epidermis (skin)|epidermis]]. (''[[M. ulcerans]]'' infection, S100 [[immunoperoxidase|immunoperoxidase stain]].)]]
[[File:The representation of Langerhans cells in the Cell Ontology.jpg|thumb|300px|The representation of Langerhans cells in the Cell Ontology. A portion of the Cell Ontology is shown with ovals corresponding to cell types defined in the ontology and arrows corresponding to relations between those cell types. Langerhans cell is represented by a yellow oval; blue arrows correspond to is_a relations, and orange arrows correspond to develops_from relations. Only a subset of Langerhans cell parent types are included in the figure.<ref name="pmid19243617">{{REFjournal
|last=Masci
}}</ref>]]
'''Langerhans cells''' are dendritic cells (antigen-presenting immune cells) of the [[skin ]] and [[mucosa]], and contain large granules called Birbeck granules. They are present in all layers of the epidermis, but are most prominent in the stratum spinosum.<ref name="Wheaters">{{REFbook
|last=Young
|first=Barbara
|init=B
|last2=Heath
|first2=John W.
|init2=JW
|year=2000
|title=Wheater's Functional Histology
|accessdate=
|note=
}}</ref> They also occur in the papillary dermis, particularly around blood vessels,<ref name=Wheaters /> as well as in the oral [[mucosa]], [[foreskin]], and [[vagina]].<ref name=pmid7558138 /> They can be found in other tissues, such as lymph nodes, particularly in association with the condition Langerhans cell histiocytosis (LCH).
== History ==
|init=P
|title=Über die Nerven der menschlichen Haut
|trans-title=On the nerves of the human [[skin]]
|language=German
|journal=Archiv für Pathologische Anatomie und Physiologie und für Klinische Medicin
}}</ref>
==Function== In [[skin ]] infections, the local Langerhans cells take up and process microbial antigens to become fully functional antigen-presenting cells.
Generally, dendritic cells in biological tissue are active in the capture, uptake and processing of antigens. Once dendritic cells arrive in secondary lymphoid tissue, however, they lose these properties while gaining the capacity to interact with naive T-cells.
=== LCH ===
In the rare disease Langerhans cell histiocytosis (LCH), an excess of these cells is produced. This can cause damage to [[skin]], bone and other organs.
=== HIV ===
====Former hypothesis====
Kawamura ''et al''. (2005) suggested Langerhans cells may be initial cellular targets in the sexual transmission of [[HIV]],<ref>{{REFjournal
|last=Kawamura
|first=Tatsuyoshi
}}</ref>
Hussain & Lehner (2005) observed Langerhans cells have been observed in foreskin, vaginal, and oral [[mucosa ]] of humans; the lower concentrations in oral [[mucosa ]] suggest that it is not a likely source of [[HIV]] infection relative to foreskin and vaginal [[mucosa]].<ref name="pmid7558138">{{REFjournal
|last=Hussain
|init=LA
}}</ref>
====Present view====
On 4 March 2007 the online ''Nature Medicine'' magazine published the letter "Langerin is a natural barrier to HIV-1 transmission by Langerhans cells."<ref>{{REFjournal |last=De Witte |first=Lot |init=L |last2=Nabatov |first2=Alexey |init2=A |last3=Pion |first3=Marjorie |init3=M |last4=Fluitsma |first4=Donna |init4=D |last5=De Jong |first5=Marein A.W.P. |init5=MAWP |last6=De Gruijl |first6=Tanja |init6=T |last7=Piguet |first7=Vincent |init7=V |last8=Van Kooyk |first8=Yvette |init8=Y |last9=Geijtenbeek |first9=Teunis B.H. |init9=TBH |title=Langerin is a natural barrier to HIV-1 transmission by Langerhans cells |journal=Nature Medicine |volume=13 |issue=3 |pages=367-371 |url=https://www.nature.com/articles/nm1541 |quote= |pubmedID=17334373 |pubmedCID= |DOI=10.1038/nm1541 |date=DeWitte etal 2007-03-04 |accessdate=2019-10-19}}</ref> One of the authors of the study, Teunis Geijtenbeek, said that "Langerin is able to scavenge viruses from the surrounding environment, thereby preventing infection" and "since generally all tissues on the outside of our bodies have Langerhans cells, we think that the human body is equipped with an antiviral defense mechanism, destroying incoming viruses."<ref>{{REFnews
|last=Mundell
|first=E. J.
}}</ref>
== Population-based studies ==
{{Population-based studies}}
==Two African surveys==
The previously reported studies were from developed Western nations. Now we have information from Sub_Saharan Africa.
French scientist [[Michel Garenne]], Ph.D. has published two reports in 2022 comparing the incidence of HIV infection in [[circumcised]] and [[intact]] men.
In his first report, Garenne presented the findings from a study in Lesotho, the enclave in South Africa. He reported:
<blockquote>
In couple studies, the effect of circumcision and VMMC on HIV was not significant, with similar transmission from female to male and male to female. The study questions the amount of effort and money spent on VMMC in Lesotho.<ref name="garenne2022A">{{REFjournal
|last=Garenne
|first=Michel
|init=M
|author-link=Michel Garenne
|title=Changing relationships between HIV prevalence and circumcision in Lesotho
|url=https://pubmed.ncbi.nlm.nih.gov/35373731/
|date=2022-04-04
|journal=J Biosoc Sci
|volume=online ahead of print
|pages=1-16
|DOI=10.1017/S0021932022000153
|pubmedID=35373731
|accessdate=2022-10-28
}}</ref>
</blockquote>
In his second report, Garenne (2022) presented information from six Sub-Saharan African nations (Eswatini, Lesotho, Malawi, Namibia, Zambia, Zimbabwe). He reported:
<blockquote>
"Results matched earlier observations made in South Africa that [[circumcised]] and [[intact]] men had similar levels of HIV infection."<ref name="garenne2022B">{{REFjournal
|last=Garenne
|first=Michael
|init=M
|author-link=
|etal=no
|title=Age-incidence and prevalence of HIV among intact and circumcised men: an analysis of PHIA surveys in Southern Africa
|trans-title=
|language=
|journal=J Biosoc Sci
|location=
|date=2022-10-26
|season=
|volume=
|issue=
|article=
|page=
|pages=1-13
|url=https://www.cambridge.org/core/journals/journal-of-biosocial-science/article/abs/ageincidence-and-prevalence-of-hiv-among-intact-and-circumcised-men-an-analysis-of-phia-surveys-in-southern-africa/CAA7E7BD5A9844F41C6B7CC3573B9E50
|archived=
|quote=
|pubmedID=36286328
|pubmedCID=
|DOI=10.1017/S0021932022000414
|accessdate=2022-10-27
}}</ref></blockquote>
{{SEEALSO}}
* [[Foreskin]]
* [[Immunological and protective function of the foreskin]]