The assessment of cellular proliferation by immunohistochemistry: a review of currently available methods and their applications

Immunohistochemical assessment of cell proliferation in plant tissues using formaldehyde-fixed paraffin-embedded material

Cell proliferation in formaldehyde-fixed and wax-embedded sections of root tissues from Vicia faba beans was assessed by using a monoclonal antibody raised against the proliferating cell nuclear antigen (PCNA). Positive PCNA immunoreactivity was restricted to nuclei in known proliferating zones of the root. The immunoreactivity of cells in metaphase/anaphase of mitosis showed weaker PCNA immunoreactivity while nuclei in telophase showed no PCNA immunoreactivity indicating that this method is well suited to label proliferating cells in plant tissues.

Bromodeoxyuridine and iododeoxyuridine double immunostaining for epoxy resin sections

To establish bromodeoxyuridine (BrdUrd)/iododeoxyuridine (IdUrd) double immunostaining for thick sections of epoxy resin-embedded tissues, young hamsters received intra-peritoneal injections of IdUrd and BrdUrd 3 hr and 1 hr before sacrifice, respectively. The intestines were fixed with phosphate-buffered 4% paraformaldehyde and embedded in an Epon-Araldite mixture. The epoxy resin was removed completely by a sodium methoxide/benzene/methanol solution. This epoxy resin removal method was effective for BrdUrd/IdUrd immunostaining using a mono-specific antibody for BrdUrd (Br-3) and a bi-specific antibody for BrdUrd (Br-3) and a bi-specific antibody for BrdUrd and IdUrd (IU-4), followed by the ABC complex method. Epoxy sections stained with these antibodies showed clear localization of nuclei incorporating the two thymidine analogues with precise morphology of labeled cells. Furthermore, ultrastructural observation of thin sections adjacent to thick sections immunostained for BrdUrd/IdUrd confirmed the cell type and ultrastructural features of cells labeled with these thymidine analogues.

Immunohistochemical analysis of proliferation and differentiation in organotypic cultures of cervical tumor cell lines

Researchers have previously demonstrated that organotypic cultures of cervical tumor cell lines exhibit morphological characteristics similar to the in vivo biopsies from which they were derived (Rader et al., 1990). Both the in vivo biopsy and organotypic culture appeared undifferentiated. We have extended these studies with immunohistochemical analysis using the proliferation and differentiation markers, proliferating cell nuclear antigen (PCNA) and involucrin, respectively, to evaluate in more detail the ability of cervical tumor cell lines to differentiate in organotypic culture. An HPV-immortalized keratinocyte cell line, PE-4, expressed PCNA in the lower half and involucrin in the upper half of the organotypic culture which is consistent with the characteristics of a preneoplastic lesion in vivo. The CC-1 cell line, derived from an invasive squamous cell carcinoma, appeared undifferentiated, but expressed involucrin in the upper half of the organotypic culture. This is the first observation of expression of a differentiation marker in an organotypic culture of a cervical tumor cell line. The other cervical tumor cell lines, SiHa and HeLa, derived from a squamous cell carcinoma, and an adenocarcinoma of the cervix, respectively, did not express detectable levels of involucrin or mucin. All three cervical tumor cell lines, CC-1, SiHa and HeLa, expressed PCNA throughout their entire thickness. The majority of nuclei in SiHa and HeLa cultures were PCNA-positive, while the CC-1 cell line exhibited a lower growth fraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Oncogene proteins and proliferation antigens in thymomas: increased expression of epidermal growth factor receptor and Ki67 antigen

AIMS

To examine thymomas for proteins encoded by oncogenes and to determine whether their presence correlates with tumour growth and associated myasthenia gravis.

METHODS

Sections of 24 thymomas were incubated with anti-EGF receptor (EGF-R), anti-Ki67 antigen, anti-p53, and anti-bcl-2 antibodies, and then stained using the alkaline phosphatase/anti-alkaline phosphatase (APAAP) technique. Cell suspensions and epithelial cell cultures from some of the tumours were also studied.

RESULTS

Whereas EGF-R expression was not detected in any of the controls (but only in a 20 week old fetus), it was detected in neoplastic epithelial cells of all thymomas, and was most strongly expressed in metastases and in samples from donors with severe myasthenia gravis. Ki67 labelling was also increased, especially in the larger thymomas. Epithelial expression of both of these markers was confirmed in fresh cell suspensions and monolayer cultures from the five available cases. In contrast, p53 and bcl-2 were not detected in the neoplastic cells, but bcl-2 was present in the intermingling thymocytes.

CONCLUSIONS

Neoplastic thymoma cells express EGF-R and Ki67, but there is no concomitant increase in the expression of p53 and bcl-2 proteins. Increased EGF-R expression may result in increased proliferation of neoplastic cells and also in myasthenia gravis. Measurement of EGF-R concentrations may be of prognostic value. The bcl-2 staining pattern in T lymphocytes illustrates the broad spectrum of maturational stages in thymoma lymphocytes.

Clinical and Histological Prognostic Factors in Axillary Node-Negative BreastCancer: Univariate and Multivariate Analysis with Relation to 5-Year Recurrence

In the recent years several studies have shown that about 30% of cases with axillary node-nagative breast cancer suffer relapse of the disease. Our attempt was made to evaluate the most significant prognostic factors to predict this high risk group which may be benefited from adjuvant treatment. For this purpose, we selected 9 patients out of 80 cases of node-negative breast cancer who had been followed up at least for 5 years and had the recurrence of the disease. For comparison, 16 patients from the same group who did not have relapse were selected on a random basis. Histology, receptor status, AgNOR, DNA flow cytometry and various immunohistochemical parameters were compared between the groups with recurrence and that without recurrence. On univariate analysis, tumor size, immunohistochemical expressions of PCNA, MIB-1, c-erbB-2 and S-phase fraction were significantly different between the above two groups. By multivariate analysis, immunohistochemical c-erbB-2 expression (more than 50% of cancer cells) was an independent parameter. As a summary from our studies, c-erbB-2 immunohistochemical staining on paraffin sections might be the best independent prognostic factor in axillary node-negative breast cancers.

Assessment of cellular proliferation of sebaceous neoplasms by AgNOR counts and immunohistochemical demonstrations of PCNA and Ki-67

We assessed cellular proliferation of sebaceous neoplasms by AgNOR counts and the immunohistochemical demonstration of proliferating cell nuclear antigen (PCNA) and Ki-67, using formalin-fixed and paraffin-embedded tissue specimens. We used three categories of sebaceous neoplasms: four cases of sebaceoma, three cases of basal cell carcinoma with sebaceous differentiation (BCSD), and seven cases of sebaceous carcinoma (SC). Significant differences were noted between SC and non-SC tumors (sebaceoma and BCSD) in AgNOR counts and semi-quantitative grading of PCNA and Ki-67 labelling indices (P < 0.01). When a cut-off value of 6 was chosen, the AgNOR value discriminated SC from non-SC tumors with high specificity and sensitivity. When a cut-off value of 25% was chosen, PCNA and Ki-67 labelling indices also discriminated between these tumors. Significant differences were not observed between sebaceoma and BCSD with PCNA and Ki-67 labelling indices. AgNOR counts of BCSD were a little higher than those of sebaceoma, but the number of cases was too small to perform statistical assessment. We consider AgNOR counts and semi-quantitative grading of PCNA and Ki-67 labelling indices to be useful in differentiating SC from BCSD and sebaceoma.

Use of in situ detection of histone mRNA in the assessment of epidermal proliferation: comparison with the Ki67 antigen and BrdU incorporation

The labelling index is commonly used as a measure of proliferation. However, the use of tritiated thymidine or BrdU labelling of S-phase cells is limited to prospective samples. We have employed an oligonucleotide cocktail complementary to the mRNA species encoding the replication-dependent histones H2B, H3 and H4 for non-isotopic in situ hybridization (NISH), and have compared the resultant proliferation indices in normal skin with those obtained by bromodeoxyuridine (BrdU) incorporation and by Ki67 immunohistochemistry (IHC) using the monoclonal antibody MIB1. In addition, we compared the staining characteristics of histone NISH and Ki67 IHC in a further 25 samples from a variety of inflammatory dermatoses and neoplastic conditions, as well as from normal skin. In normal skin, S-phase (histone NISH and BrdU) and cycling (Ki67) cells were confined to the basal and low suprabasal layers. The labelling indices determined by histone NISH and BrdU incorporation were similar, whereas that of Ki67 IHC was four times greater. In biopsies from hyperproliferative dermatoses and dysplastic or malignant lesions, the number of histone NISH- and Ki67 IHC-positive cells was generally elevated; in accordance with the differential expression of these two markers during the cell cycle, MIB1 consistently gave higher results. The advantage of histone NISH over Ki67 IHC is that it is a marker of the same part of the cell cycle as BrdU incorporation. However, the combined use of both histone NISH and Ki67 IHC to measure two cell cycle parameters, namely S-phase and the number of cycling cells, allows more detailed retrospective study of epidermal proliferation than has been possible previously.

Comparison of proliferating cell nuclear antigen (PCNA) staining and BrdUrd-labelling index under different proliferative conditions in vitro by flow cytometry

PC10 is a monoclonal antibody against proliferating cell nuclear antigen (PCNA). The staining pattern in immunochemistry depends on fixation and detergent extraction treatment. The aim of this study was to validate the flow cytometric PCNA assay against Bromodeoxyuridine-labelling index (BrdUrd-LI) under different proliferative conditions in vitro. Expression of PCNA in methanol fixed cells with, and without, prior detergent extraction with EDTA/Triton was compared to BrdUrd-labelling index in NIH-3T3 fibroblasts and human Caski tumour cells in exponential phase and under confluent conditions. Serum stimulation and serum starvation conditions were studied. The results for BrdUrd-LI and PCNA-index after extraction showed good correlation for 3T3 fibroblasts and for Caski cells, with some differences for serum withdrawn Caski cells. There was no correlation between the number of cells that were positive for PCNA without extraction and BrdUrd-LI. Spheroid cells with G1-DNA-content showed an almost synchronous recruitment and progression through the cell cycle after trypsination and replating. Tightly bound PCNA paralleled this synchronicity whereas total PCNA did not change significantly. The results demonstrate that immunochemical detection of non-extractable PCNA-index gives similar results as compared with BrdUrd-labelling index under different proliferative conditions in vitro for different monolayer cell lines, whereas without extraction PCNA does not correlate with BrdUrd-LI in these fast growing cell lines due to its long half-life. PCNA expression parallels the progression through the cell cycle in V79 spheroids, a primitive model of tumour growth.

Division of labor among gonadotropes

This chapter has presented a somewhat complex view of the gonadotrope population, indicating that it consists of independent subsets. There may be regulatory cells that influence development and other ancillary processes needed for normal reproduction. For example, normal differentiation of PRL cells requires a functioning population of gonadotropes (Kendall et al., 1991). In addition, gonadotropes appear to be autoregulatory; subsets may produce inhibin or activin (in rats) and follistatin. Production of GnRH itself may serve as another regulatory tool. The gonadotrope population appears to be quite dynamic and convertible in the female rat. Cytological and cytochemical changes with the stage of the cycle are obvious. Increases in the numbers of immunoreactive gonadotropes parallel increases in GnRH target cells and culminate in peak expression of LH and FSH beta subunit mRNAs. The immunoreactive gonadotropes are greatly reduced after the surge activity, as though the cells had disappeared from the population. However, gonadotropes can still be detected by their content of gonadotropin mRNAs. This finding has led to the hypothesis that the gonadotropes recycle themselves. However, do they go through a resting phase? Is there a normal cycle of cell death and turnover? These are basic questions that must be answered in order to understand how the population is organized and renewed. Finally, we have returned to one of our original problems. Whereas it is clear that nonparallel release can be brought about by granules or cells with only one gonadotropin, the exact mechanisms that sort the gonadotropin molecules or turn off bihormonal expression are not known. A combination of autoregulatory events involving follistatin, activin, inhibin, and possibly steroids may play a role in modulating expression by a given subset. Delays in maturation may also prevent secretion of FSH and, hence, effect the delayed rise seen during late proestrus. The nonsecretory FSH cells seen in the studies by Lloyd and Childs (1988a) may be delayed maturers, requiring additional receptor types or changes in the calcium flux pattern to secrete their product. We also have a new question to address. What is the significance of the presence of GH in proestrous gonadotropes? Is GH a regulatory hormone, bound to receptors inside gonadotropes, or do subsets of somatotropes augment the population, producing a cocktail of GH and gonadotropins to aid ovulation? Either hypothesis is intriguing. Co-storage of GH and gonadotropins would be an efficient way of providing the hormones needed by the ovary. However, further work with in situ hybridization is needed to detect GH mRNA in such cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Assessment of cellular proliferation of eccrine acrospiromas and eccrine sweat gland carcinomas by AgNOR counting and immunohistochemical demonstration of proliferating cell nuclear antigen (PCNA) and Ki-67

Argyrophil nucleolar organizer regions (AgNORs) were counted and immunostaining using antibodies raised against proliferating cell nuclear antigen (PCNA) and Ki-67 was carried out on eccrine acrospiroma and eccrine sweat gland carcinoma, to determine the malignant potential and prognosis of these tumours. Formalin-fixed and paraffin-embedded tissue specimens surgically excised from 25 patients with eccrine sweat gland carcinoma (20 cases of eccrine porocarcinoma, four cases of ductal sweat gland carcinoma and one case of malignant clear cell hidradenoma) and 25 patients with eccrine acrospiroma (16 cases of eccrine poroma, four cases of poroid hidradenoma and five cases of clear cell hidradenoma) were used. PCNA and Ki-67 labelling indices were categorized semiquantitatively into four grades. Significant differences were noted between eccrine sweat gland carcinoma and eccrine acrospiroma with these three methods (P < 0.01). When a cut-off of 5 was chosen, the AgNOR value distinguished eccrine sweat gland carcinoma from eccrine acrospiroma with high specificity and sensitivity. Moreover, we compared the results of these three methods between stages 1 or 2 (17 cases) and stage 3 (eight cases) eccrine sweat gland carcinomas, and no significant differences were observed. From these findings, these three methods are useful in discriminating malignant from benign lesions of eccrine tumours, but have no value in estimating the aggressiveness of eccrine sweat gland carcinomas.

Assessment of cell proliferation by means of an enzyme-linked immunosorbent assay based on the detection of the Ki-67 protein

A new ELISA system for the estimation of cell proliferation based on the detection of the Ki-67 protein is described. This protein has turned out to be strictly correlated to all active parts of the cell cycle, i.e., G1, S, G2, and mitosis, but is absent in G0. In addition, it is not detectable during DNA repair. In cultures of cell line cells as well as stimulated peripheral blood cells the values obtained with this ELISA system paralleled the [3H]thymidine uptake in different cell cultures. Thus, this assay provides a simple, non-radioactive assessment of proliferation of cultured cells.

Assessment of proliferative activity in type II pneumocytes after inhalation of NO2 by AgNOR-analysis

Adult male Sprague Dawley rats were exposed to 0.8, 5 and 10 ppm NO, alternatively for 1 or 3 days. After exposure the proliferative activity of the airway epithelium was assessed by means of BrdU incorporation and AgNOR-analysis at three different airway levels--in the bronchial, the bronchiolar epithelium and in Type 2 cells. The BrdU-labeling index (BrdU-LI), and AgNOR-number (AgNOR-N) were used to quantify the epithelial proliferation. Cytologic specimens of Type II cells showed a significant increase of the AgNOR-number and BrdU-LI after exposure to 5 ppm NO2 for 3 days and 10 ppm for 1 and 3 days. In the bronchiolar epithelium both, the AgNOR-number and BrdU-LI were significantly elevated in all the exposure groups. In the bronchial epithelium a significant response of the AgNOR-number was found after exposure to 10 ppm for 3 days. The correlation between AgNOR-number and BrdU-LI was 0.78 (p < 0.005).

In situ analysis of cellular proliferation in canine, feline and equine tumors by immunohistochemistry: a comparison of bromodeoxyuridine, proliferating cell nuclear antigen, and interchromatin-associated antigen immunostaining techniques

Cell proliferation in canine, feline, and equine tumors was evaluated using immunohistochemical detection of in vitro 5-bromodeoxyuridine (BrdU) incorporation, proliferating cell nuclear antigen (PCNA), and interchromatin-associated antigen (p105). Ten tumors in each species were analyzed. The tumor proliferative fraction (PF) was defined as the percentage of labeled nuclei for 5,000 tumor nuclei counted. Immunoreactivity was observed with all techniques in all species. A good correlation was observed between the proliferative fractions measured with the BrdU (PFBrdU) and PCNA (PFPCNA) techniques (rs = 0.523, P = 0.0026). There was no correlation between the PFs measured with the BrdU (PFBrdU) and p105 (PFP105) techniques. Using the median values obtained from the different approaches as cutoff points to define slowly and rapidly proliferating tumors, there was an 80% agreement (P = 0.009) between PFBrdU and PFPCNA and no agreement between PFBrdU and PFP105. The results of this study indicate that both BrdU and PCNA labeling methods can be used reliably for identifying proliferating cells in animal tumors. In addition, PCNA could be used to replace the BrdU method to assess tumor proliferative fraction because it does not require pretreatment of tissues.

Sclerotic fibroma: a fossil no longer

We report on a patient with a sclerotic fibroma that recurred 30 months after initial removal. The histologic features were characteristic, and immunoperoxidase stains using primary antibodies directed against cell proliferation markers were positive in a significant proportion of the neoplastic nuclei. A review of the literature identified one other sclerotic fibroma that persisted. These clinical and light microscopic features support the interpretation that sclerotic fibroma is a proliferating neoplasm with an unusual histologic pattern, rather than the end-stage of a process that was formerly more cellular. We advocate use of sclerotic fibroma as the preferred diagnostic term.

Adult rhabdomyoma. A light microscopic, ultrastructural, virologic, and immunologic analysis

Adult rhabdomyoma is a rare benign tumor of skeletal muscle origin that frequently arises from musculature of the head and neck region. In this study we report five cases of adult rhabdomyoma. Light and electron microscopic examination revealed the typical cellular features as described by others. The results of immunophenotyping and quantitation of nucleolar organizer regions were consistent for a benign skeletal muscle tumor. Epstein-Barr virus and human papillomavirus genomic DNA could not be detected by in situ hybridization.

Changes of colon epithelium proliferation due to individual aging with cyclin proliferating cell nuclear antigen (PCNA/cyclin) immunostaining compared to [3H]-thymidine radioautography

We report a change in the proliferative activity of mouse colonic epithelium due to development and aging. In order to measure the proliferative activity, colonic epithelium was immunostained for cyclin proliferating cell nuclear antigen (PCNA/cyclin), which appears from the Gl to the S phase of the cell cycle, and compared with labeling obtained by [3H]-thymidine radioautography. Litter mice of six age groups from the fetal period (embryonic day 19), newborn period (postnatal day 1), suckling period (postnatal day 5), weaning period (postnatal dy 21), adult period (2 month old) to the senescent period (11 month old) were examined by immunohistochemistry. The descending colons were fixed in methacarn (method-Carnoy) and embedded in paraffin. Sections were stained for PCNA/cyclin activity using 19A2 monoclonal antibody and the avidin-biotin peroxidase complex (ABC) technique. For radioautography, litter mice of nine age groups using in vivo intraperitoneal administration of [3H]-thymidine. The labeling indices of colonic epithelial cells in the proliferative zone were then analyzed and compared between the two investigative methods. Our results show that the proliferative activity of mice colon was high in the fetal and newborn periods and almost constant from the suckling period to senescence, as demonstrated by both PCNA/cyclin immunohistochemistry and [3H]-thymidine radioautography. The labeling index seen by PCNA/cyclin immunohistochemistry was, however, higher than that seen by [3H]-thymidine radioautography.

Proliferating cell nuclear antigen in normal urothelium and urothelial lesions of the urinary bladder: a quantitative assessment using a true color image analysis system

To evaluate proliferating cell nuclear antigen (PCNA) staining for assessing proliferative activity in routine pathology specimens of urinary bladder, the bladder carcinoma cell line J82 and a total of 122 specimens of normal bladder and urothelial lesions were stained with the antibody clone PC10 against proliferating cell nuclear antigen. In in vitro plateau cultures the proportion of PCNA-positive cells exceeded that of Ki-67-positive cells, and only very few cells were negative. In formalin-fixed tissues, the PCNA staining pattern, which should be confined to replicon units in the nucleus, was optimized by 1 h postfixation in an organic solvent (methacarn). Sections showed positive nuclear staining confined to basal and some suprabasal cells in normal urothelium and grade 1 dysplasias, but more generalized nuclear staining in all other neoplastic lesions. In addition, stromal cells adjacent to invasive tumors showed nuclear positivity in some instances. Using quantitative true color image analysis of sections counterstained with hemalum, the degree of brown staining of the PCNA reaction product is contrasted with the blue staining of the nuclear area. With this method low contrast specific staining not appreciated optically can be reliably detected. Image analysis data confirmed observations made on noncounterstained sections and showed significant differences between grade 1 and 2 dysplasias as well as between grade 1 dysplasia and all grades of papillary tumor. Furthermore, a significant difference in PCNA staining indices was found between grade 1 and 3 bladder carcinomas. The results indicate that PCNA staining using the PC10 antibody is not confined to the proliferative fraction of neoplastic urothelium.(ABSTRACT TRUNCATED AT 250 WORDS)

Over-expression of the S13 ribosomal protein in actively growing cells

In order to define biological markers of aggressiveness, 2 rat colon-carcinoma cell lines differing by their tumorigenicity were used to clone genes over-expressed in colon carcinoma as compared with normal epithelial cells. A progressive rat colon-carcinoma clone (PROb) cDNA library was hybridized with 32P-cDNA synthesized from mRNA prepared from these PROb cells, or from regressive cells (REGb) derived from the same tumor. Several clones were isolated after the initial screening. The specificity of each clone was confirmed by RNA blotting. One of these (B9) was found to hybridize to an mRNA 30-fold more abundant in PROb cells than in normal adult rat colon, and was therefore selected for further study. No gene amplification was detected by Southern blot analysis, indicating that the difference in mRNA content was most likely due to an increased transcription of this gene. Sequencing of the cDNA revealed approximately 98% homology with the rat S13 ribosomal protein. The expression level of this gene was determined in a series of rat cell lines with different growth rates. A good correlation was found between these 2 parameters. Our data suggest that the S13 ribosomal-protein gene can be used to evaluate the growth rate of tumor cells, which might be correlated with their aggressiveness. In an initial trial experiment, S13 ribosomal-protein mRNA was detected in a series of human colorectal tumors by in situ hybridization. A strong signal was seen in the 4 tumors analyzed.

Proliferative state of the urothelium with benign and atypical changes. Correlation with transferrin and epidermal growth factor receptors and blood group antigens

We attempted to investigate how the proliferative state of the urothelium correlates with the reactivity for transferrin (Tf) and epidermal grown factor (EGF) receptors and the blood group (BG) antigen. We examined morphologically normal urothelium (34 cases), benign inflammatory and reactive conditions (24 cases), and atypical changes (20 cases) without exophytic or invasive neoplasia. The Ki67 nuclear antigen was used as the proliferation index and was complemented with the in vitro BrdU incorporation assay in 32 cases. The immunohistochemical reactions for Tf and EGF receptors and for the appropriate BG antigen were scored semi-quantitatively on frozen sections. We found that normal urothelium has very low Ki67 and BrdU indices as well as low reactivity for the two receptors and is almost invariably positive for the BG antigen. Benign conditions such as inflammation and metaplasia significantly augment the proliferation indices and the Tf receptor with little change in the EGF receptor and no significant effect on the BG antigen. Moderate atypia includes biologically heterogeneous cases which vary widely in proliferation and receptor expression. Severe atypia-carcinoma in situ is consistently associated with markedly elevated proliferation indices, strong Tf receptor reactivity, and depressed BG antigen. The reactivity for EGF receptor is less consistently increased. Cases with a combination of strong EGF receptor reactions and absence of the expected BG antigen have a poor prognosis with progression to invasive cancer.

Proliferation of reactive and neoplastic human tissue mast cells. An immunohistochemical study using the antibody PC10 (anti-PCNA)

Studies on the proliferative compartment of human tissue mast cells (MCs) and their tumours (mastocytosis) have not been performed. We have used the monoclonal antibody PC10 to study MCs in reactive or hyperplastic states (chronic non-specific lymphadenitis, n = 10; benign and malignant solid tumours, n = 5) and in the various subtypes of mastocytosis (urticaria pigmentosa, n = 22; solitary mastocytoma of the skin, n = 7; systemic mastocytosis; n = 8; malignant mastocytosis, n = 4). The identification of PC10-positive MC nuclei was achieved by double staining. We found no PC10-positive MCs in reactive or hyperplastic states, or in 14 of 22 cases of urticaria pigmentosa. PC10-positive MCs could be identified in all other mastocytosis but mostly in very low numbers. The mean percentages of PC10-positive MCs amounted to 0.5 in eight positive cases of urticaria pigmentosa, 1.2 in mastocytoma, 0.7 in systemic mastocytosis, and 4.0 in malignant mastocytosis. The difference between the latter form of mastocytosis and each of the other subtypes proved to be significant (P < 0.05). The very small proliferative compartment in the cutaneous and systemic variants of mastocytosis is in accord with their favourable prognosis. Most of the patients with systemic mastocytosis in the present study are all alive and well up to 12 years after diagnosis. In contrast, most of the patients with malignant mastocytosis died within 1 year of diagnosis.

Immunohistochemical assessment of cellular proliferation in the developing human CNS using formalin-fixed paraffin-embedded material

Assessment of cell proliferation in the developing human brain has been limited to counting mitotic cells, since the other procedures currently used for determination of the mitotic activity either depend on experimental manipulation of the tissue, e.g., labeling with radioactive thymidine precursors or with bromodeoxyuridine, or on frozen sections of the tissue, e.g., Ki-67 immunoreactivity. As most of the developing human brain material available is formalin fixed and paraffin embedded, these procedures are not practical. An immunohistochemical technique based on a monoclonal antibody directed against a proliferating cell nuclear antigen (PCNA) was used for detecting cellular proliferation in the developing human brain. Known progenitor cells in proliferating zones showed distinct PCNA-reactivity, but the method also revealed new areas of cell proliferation in fixed paraffin-embedded tissue blocks from the developing human brain.

Combined proliferating cell nuclear antigen and morphometric analysis in the diagnosis of cutaneous lymphoid infiltrates

AIMS

To evaluate the use of morphometry in the diagnosis of benign and malignant cutaneous lymphoid infiltrates; and to determine whether the sensitivity of detection of cutaneous T cell lymphoma (CTCL) could be improved by selectively measuring cells expressing proliferating cell nuclear antigen (PCNA).

METHODS

44 archival biopsy specimens were studied. These included cases of CTCL, non-specific chronic dermatitis, lichen planus and lupus erythematosus. PCNA was identified using a standard immunohistological technique. Reactive cells were identified using automatic colour discrimination, and the size and shape were determined interactively. Similar measurements were made on the total dermal lymphocyte population.

RESULTS

There was no significant difference between the proportions of PCNA reactive cells in any of the diseases studied. The PCNA positive lymphocytes in CTCL were larger than those in lupus erythematosus and lichen planus and were more irregular in shape than those in chronic dermatitis. Differences were also seen in the total lymphocyte population. Plotting cell size and shape(fcircle) for PCNA cells together allowed CTCL to be differentiated from the inflammatory disorders with a sensitivity of 80% and a specificity of 93%. This was better than could be achieved using measurements made on the total cell population.

CONCLUSIONS

This technique can be partly automated and could be useful in the differential diagnosis of cutaneous lymphoid infiltrates. The result are also of some interest in the further understanding of patterns of cell proliferation in skin associated lymphoid tissue.