02299nas a2200301   4500000000100000008004100001260001600042653001500058653001100073653003000084653002800114653002100142653001800163653001200181653002500193653000900218653002000227100001300247700001300260700001500273700001100288700001300299245009700312300001100409490000800420520155500428022001401983       1987                            d  c1987 Mar 0110aCell Count10aHumans10aHypersensitivity, Delayed10aImmunoenzyme Techniques10aLangerhans Cells10aLeishmaniasis10aleprosy10aMicroscopy, Electron10aSkin10aTuberculin Test1 aKaplan G1 aNusrat A1 aWitmer M D1 aNath I1 aCohn Z A00aDistribution and turnover of Langerhans cells during delayed immune responses in human skin.  a763-760 v1653 a<p>The changes in distribution and turnover of T6+ Langerhans cells (LC) in the skin during delayed immune responses to tuberculin, and in the lesions of tuberculoid leprosy and cutaneous Leishmaniasis were investigated. In each situation, there was a dermal accumulation of monocytes and T cells and epidermal thickening with keratinocyte Ia expression. In the tuberculin response a dramatic change in the distribution of LC was observed. By 41 h, T6+ LC were displaced to the upper zone of the thickening epidermis followed by an almost complete loss of LC from the epidermis by approximately 72 h. After 7 d, T6+ cells started to reappear in the epidermis, which regained almost normal numbers of T6+ LC by 14 d. After antigen administration and initiation of the delayed immune response, enhanced numbers of T6+ cells appeared in association with the mononuclear cell infiltrate of the upper dermal lesions. Their numbers peaked by 72 h, were reduced at 7 d, and again enhanced by 14 d, when the epidermis was being repopulated. Similar numbers of T6+ cells were found in the chronic lesions of tuberculoid leprosy and cutaneous Leishmaniasis but not lepromatous leprosy. The cells of the dermis were identified as typical LC by the presence of Birbeck granules and surface T6 antigen at the electron microscope level. These cells were closely associated with lymphocytes. We have quantified the number of LC, evaluated their directional flux into the epidermis and dermis, determined nearest neighbors, and made predictions as to their fate.</p>  a0022-1007