title: Immunohistological characterisation of tumour infiltrating lymphocytes in melanocytic skin lesions.
abstract: BACKGROUND
  Although the presence of tumour infiltrating lymphocytes (TIL) is a constant feature in melanomas, their immunophenotypic characterisation is still incomplete. We hypothesise that the transition from normal skin to benign naevi (BN) to melanocytic dysplastic naevi (MDN) to radial growth phase cutaneous malignant melanoma (RGP-CMM) to vertical growth phase cutaneous malignant melanoma (VGP-CMM) is associated with alterations in TIL. This study attempted to test this hypothesis and to characterise TIL in the melanocytic skin lesions.
  
  
  METHODS
  In total, 74 lesions (12 BN, 12 MDN, 13 RGP-CMM, 26 VGP-CMM, and 11 metastatic melanomas) were examined using immunoperoxidase staining methods and antibodies targeting leukocyte common antigen (LCA+), T (CD3+) and B (CD20+) lymphocytes, and resting cytotoxic T cells (TIA-1+).
  
  
  RESULTS
  Histologically, the transitions from normal skin to BN to MDN to RGP-CMM to VGP-CMM was associated with a gradual increase in the numbers of TIL (total, parenchymal, stromal, perivascular, and epidermal TIL, as well as TIL at the base of the lesions). The numbers of TIL were higher at the stroma than at the parenchyma. Similarly, immunostaining revealed that these transitions were associated with a gradual increase in the staining values (staining intensity, percentage of positive cells, and immunoreactivity score) for LCA+, CD20+, CD3+, and TIA-1+cells. The number of CD3+ cells was higher than that of CD20+ cells. All these differences between the normal skin and the lesional ones reached statistical significance (p<0.01). The majority of CD3+ cells were TIA-1+ T cells with cytotoxic potential. Compared with primary melanomas, there was a decrease in TIL in metastatic melanomas.
  
  
  CONCLUSIONS
  The gradual increase in TIL during melanoma tumorigenesis may reflect increased antigenicity of the tumour cells. Although both humoral and cell mediated immunity are involved in melanomagenesis, the latter seems to have the major role. The immune profile of MDN suggests their intermediacy between BN and CMM.
authors.affiliation: Department of Pathology, Assiut University Hospitals, Faculty of Medicine, Assiut University, Egypt. mrh17@swissinfo.org
authors.forename: M R
authors.initials: MR
authors.lastname: Hussein
authors.forename: D A H
authors.initials: DA
authors.lastname: Elsers
authors.forename: S A
authors.initials: SA
authors.lastname: Fadel
authors.forename: A-E M
authors.initials: AE
authors.lastname: Omar
mesh_terms: D000704:Analysis of Variance; D018951:Antigens, CD20 / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis*; D017252:CD3 Complex / Q000032:analysis; D016022:Case-Control Studies; D018450:Disease Progression; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D016130:Immunophenotyping; D017493:Leukocyte Common Antigens / Q000032:analysis; D018655:Lymphocyte Count; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology / Q000473:pathology*; D008544:Melanocytes / Q000276:immunology / Q000473:pathology*; D008545:Melanoma / Q000276:immunology / Q000473:pathology*; D009367:Neoplasm Staging; D009506:Nevus / Q000276:immunology / Q000473:pathology; D012878:Skin Neoplasms / Q000276:immunology / Q000473:pathology*; D013602:T-Lymphocytes, Cytotoxic / Q000473:pathology
chemical_list: D018951:Antigens, CD20; D014408:Biomarkers, Tumor; D017252:CD3 Complex; D017493:Leukocyte Common Antigens