Demonstration of cells bearing the OKT6 determinant in human tonsil and lymph node

Abundant dendritic cells express HLA-DR in pleomorphic adenomas

Most pleomorphic adenomas were found to contain abundant dendritic cells (DC) with major histocompatibility complex (MHC) class II (HLA-DR) expression. Their immunohistochemical staining features were suggestive of dendritic histiocytic cells. Extensive phenotypic characterization by two-colour immunofluorescence staining for various cell markers was performed. The DC expressed both HLA class I and II determinants, vimentin, S-100 protein, and various monocyte-related markers (10G11, 3D10, 7G5 or CD11a, 8C2) but were negative for leucocyte common antigen (CD45), Leu-6 (CD1), and the myelomonocytic L1 antigen. Characterization of HLA-DR positive DC isolated by an immunomagnetic bead method confirmed the immunohistochemical staining pattern that corresponds to the phenotype of interdigitating cells. Morphological and immunological implications of the abundant presence of these cells in pleomorphic adenomas are discussed.

Immature T lymphocytes after injury characterized by morphology and phenotypic markers

Changes in the peripheral blood mononuclear cell (PBMC) population in patients following both thermal and nonthermal injury were defined by both morphological characteristics and surface phenotype with the monoclonal antibodies T6, OKT9, OKT10, and OKIa1, using a fluorescence activated flow cytometer with gating to separate small cells of the lymphocyte series from larger forms. Lymphocytes with surface antigens that bind T6, OKT9, and OKT10 are rarely found in the peripheral blood of adult patients, except in those with malignancies of the lymphoid system. In both burn and trauma patients the percentage of lymphocytes in the PBMC population after Ficoll-Hypaque separation was significantly reduced as compared with normal controls due to increases in the number of granulocytes, large granular lymphocytes (LGL), and monocytes, often present in immature forms. T6 cells were found in significantly greater numbers in both burn and nonthermal injury patients than in a control group using both small and wide gate settings on the fluorescence-activated flow cytometer. Significant increases in the number of T9+ cells also were observed in both groups for a prolonged period following injury. Significantly increased numbers of the T10+ and Ia1+ cells were detected in burn patients. The response to injury, therefore, involves the appearance in the peripheral blood of immature cells that may express T6, T9, T10, and Ia1 surface antigens. These cells may be present in quantities otherwise seen only in malignant disease.

Leu-6-expressing cells in lymph nodes: dendritic cells phenotypically similar to interdigitating cells

Leu-6 is an antigen expressed by immature T cells, Langerhans cells, and indeterminate cells, the latter two of which are dendritic cells found predominantly within the skin. In dermatopathic lymphadenopathy, the paracortex is expanded by T cells and dendritic cells, including Langerhans cells. While the paracortex also contains Leu-6+ cells, the nature of such cells in lymph nodes has been controversial. To determine the characteristics of Leu-6+ paracortical cells, their morphologic, antigenic, and enzymatic features were studied in lymph nodes showing dermatopathic lymphadenopathy or reactive follicular hyperplasia. Immunologic studies with plastic, frozen, and paraffin sections demonstrated a dendritic cell morphology, a dendritic cell lineage phenotype (L3B12+, HLA-A,B,C+, HLA-DR+, S-100+), and the absence of T-cell lineage phenotype. These findings were corroborated by the enzymatic phenotype of these cells observed in plastic sections (membrane ATPase+, weak paranuclear acid phosphatase+, weak paranuclear alpha-napthylacetate esterase+). Although all paracortical dendritic cells were otherwise identical, only a subset of these cells were Leu-6+. The close phenotypic similarity between these Leu-6+ and Leu-6- paracortical dendritic cell subsets suggests a close ontogenetic relation. Furthermore, the greater abundance of the Leu-6+ subset in dermatopathic lymph nodes than in nodes exhibiting only reactive follicular hyperplasia, in conjunction with the presence of Leu-6+ dendritic cells within the sinuses of dermatopathic lymph nodes, suggests that at least some of the paracortical Leu-6+ cells are Leu-6+ Langerhans cells or indeterminate cells derived from the skin via the afferent lymphatics.

The paracortical area in reactive lymph nodes demonstrating sinushistiocytosis. An enzyme- and immunohistochemical study

The enzyme and immunohistochemical features of lymphnodes showing sinus histiocytosis have been studied. Sinus histiocytes with phenotype OKM1+ OKT4+ Leu3a+ To5+ OKIal- showed strong acid phosphatase and non-specific esterase, weak endogenous peroxidase and no ATPase activities. In nine out of ten lymph nodes, paracortical collections of dendritic OKT6+ OKIal+ cells were observed. In two of the four cases studied these dendritic cells showed strong ATPase activity. We suggest that the dendritic OKT6+ OKIal+ ATPase+ interfollicular cells represent newly arrived veiled cells (VC) which have entered the lymph node by the afferent lymph, settled in the interfollicular area and are probably involved in the induction of a cellular immune response. OKT6+ OKIal+ ATPase+ VC may subsequently transform into mature, OKT6- OKIal+ ATPase+ interdigitating reticulum cells which are involved in the negative feedback of the cellular immune response. The association with sinus histiocytosis is probably related to the fact that an increase in mononuclear phagocytes in the afferent lymph is accompanied by a relative increase in VC. Our results demonstrate that in lymph nodes showing sinus histiocytosis, two cell types increase in number, i.e. an Ia- sinusoidal cell, engaged in phagocytosis of foreign material, and an Ia+ dendritic cell in the interfollicular area, probably involved in the induction of a cellular immune response.

Langerhans cells in human papillomavirus (HPV) lesions of the uterine cervix identified by the monoclonal antibody OKT-6

The local inflammatory cell infiltrates in 263 cervical punch biopsies of the women followed-up since 1981 (16 +/- 14 months, mean +/- S.D.) for an established human papillomavirus (HPV) lesion with or without concomitant cervical intraepithelial neoplasia (CIN) were analysed for occurrence of Langerhans cells, defined by the monoclonal antibody OKT-6 using the avidin-biotin peroxidase complex (ABC) technique. OKT-6+ cells remained at the constant low level (1.5-1.9% of the inflammatory cells) in the different types of HPV lesions (flat, inverted or papillomatous condylomas), their percentages (range 0.8-2.1% of the cells) being slightly affected by the grade of HPV-associated CIN, however, (P less than 0.05 between HPV-CIN I and HPV-CIS). Although cervical HPV lesions characteristically are a disease of young females, the relative levels of in situ Langerhans cells did not show any age-dependence. Furthermore, the intensity of the inflammatory cell infiltrate did not correlate with the relative levels of OKT-6+ cells in the biopsies. Practically identical (1.6%) levels of OKT-6+ cells were found in the first biopsies of the HPV lesions shown to regress during the follow-up period (28.8% of cases), when compared with those (1.7%) in the lesions persisted (52.1% of cases) or progressed (19.1% of lesions). The results are discussed in terms of the proposed immune surveillance function against viral infections, attributed to Langerhans cells in the SALT/MALT concept.(ABSTRACT TRUNCATED AT 250 WORDS)