Search

Haematoxylin and eosin, and Giemsa stained sections from 100 peripheral T-cell lymphomas were examined blind on two occasions by four experienced haematopathologists in order to evaluate the inter- and intra-observer reproducibility of the updated Kiel classification for these malignancies. In all cases, the T-cell phenotype had been established previously in frozen section using a panel of monoclonal antibodies. Analysis by kappa statistics showed poor reproducibility, both overall and for most subtypes, with the exception of large cell anaplastic lymphoma. The distinction between low- and high-grade lymphomas was also unsatisfactory. These results indicate the need for improved precision in the definition of histological categories of peripheral T-cell lymphoma. The reproducibility of the updated Kiel classification for peripheral T-cell lymphomas in its present form is inadequate.

Oral hairy leukoplakia is an epithelial lesion of the tongue associated with productive infection by Epstein-Barr virus (EBV). However, no data concerning the pattern of EBV latent gene expression have been reported, and it remains unresolved whether true latent infection occurs in basal cell layers of oral hairy leukoplakia. We have studied six cases of oral hairy leukoplakia using monoclonal antibody immunohistology for EBV latent--EB nuclear antigen (EBNA) 1, EBNA 2 and latent membrane protein 1 (LMP 1); immediate-early (BZLF1); and replicative (EA, VCA, MA) proteins, and for the EBV-receptor (CD21 antigen). EBV DNA was demonstrated by nucleic acid in situ hybridization. Mid- to upper-zone keratinocytes contained EBV DNA and co-expressed EBNA 1, EBNA 2 (5 of 6 cases), LMP 1, BZLF1 protein, EA, VCA and MA. No EBV genome or gene expression could be demonstrated in basal or parabasal cells. Spinous keratinocytes were labelled by anti-CD21 antibodies HB5 and B2, but did not express the EBV-receptor as defined by reactivity with OKB7. The co-expression of latent and replicative infection-associated antigens is striking, indicating possible functional roles for latent proteins during the productive cycle. Our results suggest that oral hairy leukoplakia is caused by repeated direct infection of upper epithelial cells with virus from saliva or adjacent replicatively infected cells, rather than by a latent EBV infection of basal epithelial cells with a differentiation-dependent switch to productive infection as previously proposed.

The development of monoclonal antibodies and of techniques for demonstrating antigens in situ in frozen tissue sections has been responsible for remarkable progress in diagnostic histopathology. We explored the potential of these techniques when applied to post mortem tissues that were frozen at various intervals after death and stained by monoclonal antibodies using immunoperoxidase technique. The monoclonal antibodies were selected according to their reactivity with essential markers of the lymphatic system and also to their availability. Lymph nodes and splenic tissue from 30 autopsy cases were stained in addition to thymic tissue from eight deceased infants. The antigens proved to be surprisingly well preserved. Staining could be precisely evaluated with UCHT1, OKT6 and anti-Leu-7 antibodies at least 72 h after death; staining with DAKO-pan-B, DAKO-LC and anti-Leu-3a was also very reliable. Antigens expressed by T-suppressor lymphocytes and dendritic reticulum cells were less well preserved. The T8-antigen of suppressor lymphocytes was usually demonstrable in the lymph nodes but less frequently in the splenic tissues. It is concluded that most leucocyte antigens are very resistant to post mortem disintegration, and that they can be reliably interpreted by immunohistological staining using monoclonal antibodies. We therefore recommend this in autopsy specimens in cases where in-vivo examination was not feasible.

Tissue from 53 non-Hodgkin's lymphomas of high-grade malignancy according to the Kiel classification were analysed for cellular immunological markers. In most cases studies were performed in parallel on cell suspensions and cryostat sections. Histologically, the lymphomas were classified as anaplastic centrocytic (four), centroblastic (seven), Burkitt type (three), convoluted-cell type (five) lymphoblastic-unclassified (10), immunoblastic (IBL) (19) and pleomorphic T-cell type (five). Immunological phenotyping resulted in 60% B lymphomas characterized by monotypic surface membrane Ig (SmIg) and/or cytoplasmic Ig (CIg), and 23% T lymphomas with detectable E receptors; 17% of cases were non-expressive (O-type). Unusual SmIg-types were noticed in some monoclonal proliferations. Gamma (gamma) and mu chains occurred simultaneously in four cases; delta chain was the only heavy-chain in one case and a heavy-chain was absent in one case. Cases of IBL were of T-cell type in two cases, and two other cases were non-expressive. The cases of B-IBL expressed CIg in 93%, but the B lymphomas other than B-IBL only in 38%. Receptors for Fc-IgG and C3 were expressed by all major immune phenotypes (B, T, O), but were infrequent in lymphoblastic lymphoma unclassified (O-type). Adoption of immunological techniques to include frozen tissue studies was necessary in order to reach a conclusion regarding the immune phenotype in several cases.

Immunohistological methods using monoclonal antibodies have proved to be valuable in the differentiation between cells of various origins. We have previously shown most leucocyte differentiation antigens to be very resistant to post-mortem disintegration (Pallesen & Knudsen 1985). In the present study we have examined the preservation of several non-haematopoietic antigens in tissue samples of human skin, kidney, liver, pancreas, lung, thyroid gland, uterine tissue, female breast and brain from 30 autopsies performed at specific intervals after death. Frozen tissue sections were stained using monoclonal antibodies and an immunoperoxidase method. A total of 17 monoclonal antibodies against various intermediate filament proteins, epithelial antigens, various hormones and factor VIII related antigen were tested. We found surprisingly good preservation and staining of tissue antigens--even 3 d after death--in all organs except pancreas. It is concluded that many tissue antigens are fairly resistant to post-mortem disintegration and that immunohistology may be applied to diagnostic problems in human autopsy material.

The phenotype of 36 cases of hairy cell leukaemia has been investigated using a panel of monoclonal antibodies reactive with normal human lymphoid cells and with hairy cells. Staining was performed on frozen sections and/or cell smears by the recently developed APAAP immuno-alkaline phosphatase procedure. In about 90% of cases, neoplastic cells reacted strongly with antibodies against HLA-DR, leucocyte common antigen, B-cells (antibodies B1 and To15), hairy-associated antigens (antibodies KB-90, S-HCL3, HC2) and activated T-lymphocytes (antibodies anti-Tac and Tu69). The phenotype of 10% of cases was clearly different in that the neoplastic cells were negative or only weakly positive for one or more of the antigens recognized by HC2, anti-Tac and Tu69. Antibody HC1 reacted with tumour cells of only 50% of the hairy cell leukaemia cases investigated. Monoclonal antibody Ki-67 (which selectively detects proliferating cells) stained only a low percentage of cells in all but three of the cases studied. The neoplastic cells in all cases were unreactive with monoclonal antibodies anti-Leu1, Tu1, Tu33 and a meshwork of follicular dendritic cells was consistently absent from tissues infiltrated by hairy cells. The immunological phenotype associated with hairy cell leukaemia was not observed in any case of non-Hodgkin's lymphoma, suggesting that it represents a unique type of B-cell neoplasm.