Immunofluorescence detection of casein in human mammary dysplastic and neoplastic tissues

Distribution of casein-like proteins in various organs of rat

Casein-like proteins were detected in various organs of rat by use of a specific antiserum raised against rat milk caseins. The antiserum specifically recognized alpha 1-, alpha 2-, beta-, and gamma-caseins in rat milk by Western blot analysis, whereas no immunoreactive band was observed in sera of rat and fetal bovine and in bovine caseins. Immunohistochemical studies of this antiserum on formalin-fixed mammary glands showed that immunoreactive caseins were localized to the apical portion of the cytoplasm in lactating mammary epithelial cells and in the luminal secretion, which indicates a directional secretion of caseins to the lumen by the mammary epithelial cells. With this antiserum, immunoreactive substances were detected in various organs, including the pancreatic ducts and islets of Langerhans, the secretory ducts of salivary glands, zona fasciculata cells and ganglion cells of adrenal gland, distal tubules and convoluted collecting tubules of kidney, epithelial cells of bronchioles and large pneumocytes of the lung, hair follicles, sebaceous glands, and the prickle cell layer of skin, uterine glands and epithelium of the endometrium, hepatic bile ducts, and brain. In Western blot analysis, major immunoreactive substances in the above organ extracts showed a similarity in molecular weight to alpha 2-casein of rat milk. Skin was the only tissue that expressed both alpha 2- and beta-caseins. There were no other immunoreactive bands with similarity to beta- and gamma-caseins in the other organ extracts, but higher molecular weight immunoreactive bands (> 100 kD) were detected in some organ extracts, such as salivary gland, kidney, liver, lung, and uterus. These findings suggest that the alpha 2-casein-like substance is localized not only in the mammary gland but also in a variety of organs and may play an important role as a functional molecule in those organs.

Immunohistochemical markers in the identification of metastatic breast cancer

A panel of nine monoclonal and polyclonal antibodies were tested regarding specificity for metastatic breast cancer. A hundred metastatic tumors were stained, 50 of breast origin and 50 of other origins. Antibodies used were anti-alpha-lactalbumin, anti-lactoferrin, anti-casein, E29 (Dako-EMA), anti-secretory component, anti-gross cystic disease fluid protein (GCDFP15), BRST1, BRST2, and MC5. Analyses of the results were performed using chi-square and logistic regression. Positivity for MC5, BRST1, BRST2, lactoferrin, EMA, and GCDFP15 was significantly higher in tumors of breast origin than in others (p less than 0.05). Analyses of the whole panel indicated that GCDEP15 and MC5 were the best markers for identification of breast cancer metastases. When both were positive (58% of breast origin cases), the predicted probability of breast origin was 98%, compared to only 5% when both were negative. Comparison of anti-GCDFP15 with BRST2, a monoclonal antibody against the same protein, showed a slightly better sensitivity of the former, and a similar degree of specificity for breast tissue. In conclusion, a panel of antibodies can be used to securely differentiate metastatic breast cancer from other cancers in a large number of metastatic tumors of unknown origin.

Correlation between laminin and type IV collagen distribution in breast carcinomas, and estrogen receptors expression, lymph node and vascular involvement

The laminin (Lam) and type IV collagen (Coll IV) and estrogen receptor (ER) immunodetections were assessed in a large series of 400 human breast carcinomas. In all the cases the patient's age, the tumor size, the histological type and grade, the presence or the absence of axillary lymph node metastasis and of vascular invasion in tumor borders, and ER tumor content were recorded. Monoclonal anti-Lam, anti-Coll IV were applied with the avidin-biotin-peroxidase complex and monoclonal anti ER with peroxidase anti-peroxidase complex, on frozen sections. A computerized system of image analysis referred to as SAMBA (TITN) with specific software for tissue sections analysis permitted a multiparametric quantitative analysis of immunostained surfaces. With this system, in each tumor, the cellularity, the percentage of Lam, Coll IV and receptor positive surfaces versus the total cell surface and versus the epithelial (keratin positive) surface, the integrated optical density IOD histograms were obtained and correlated to morphometrical and standard histological data. From this study, it was shown that: (1) Lam and Coll IV immunostained epithelial basement membranes in carcinomas were correlated to the presence of estrogen and progesterone receptor antigenic sites within the tumors, with a significant decrease of the positive staining in ER-ICA negative tumors in comparison to ER-ICA/PR-ICA positive tumors. (2) The combined densitometric and morphometric evaluation demonstrated a decrease of Lam and Coll IV immunostaining in malignant tumors, correlated to (i) the presence of peritumorous vascular invasion and (ii) keratin positive cells in bone marrow (iii) axillary lymph node involvement. It is concluded that the variations in Lam and Coll IV antigens distribution may be relevant indicators of tumor metastatic potential in breast carcinomas and that computerized image analysis enables the standardization of the evaluation antigens distribution.

Immunodetection in fine-needle aspirates and multiparametric (SAMBA) image analysis. Receptors (monoclonal antiestrogen and antiprogesterone) and growth fraction (monoclonal Ki67) evaluation in breast carcinomas

Immunocytochemical assays (ICA) using monoclonal antiestrogen receptors (ER ICA), antiprogesterone receptors (PR ICA), and monoclonal antibody Ki67 (Ki67 ICA) were performed in 127 breast carcinomas. The immunostaining procedures were applied on frozen tissue sections, tumour imprints, and fine-needle aspirates in order to compare the variations in the distribution of the antigens detected in the three different types of preparations. Positive reactions detected with peroxidase-antiperoxidase and avidinbiotin-peroxidase, and alkaline phosphatase-antialkaline phosphatase complexes were evaluated through a computerized system of image analysis referred to as SAMBA 200 (SAMBA TITN, Grenoble, France). Application programs specifically developed for the analysis of tissue sections and of cytologic preparations were applied. This system allowed a multiparametric, accurate, reliable, reproducible and automatized evaluation of the heterogeneity of the antigenic sites in tumors. For each markers positive cell surface (PS), and integrated and mean optical densities (IOD, MOD) and IOD histograms were compared. It was shown that (1) there was no significant variation in optical densities in cell imprints and aspirates whereas PS significantly (P less than 0.01) differed in both preparations; (2) there were significant differences of the optical densities between tissue sections and cytological preparations, either imprints or aspirates, likely due to randomly cut nuclei in tissue sections; and (3) there was a significant difference between the PS of tissue sections and aspirates but no significant difference between tissue sections and imprints. It is concluded that fine-needle aspiration constitutes a convenient method for cell sampling, reliable for the diagnosis of malignancies. However, it may not reflect the heterogeneity of cell subpopulations in tissue.

Gross cystic disease fluid protein-15 as a marker for breast cancer: immunohistochemical analysis of 690 human neoplasms and comparison with alpha-lactalbumin

The identification of metastatic carcinoma of the breast may be difficult in the absence of a previous history of breast cancer. Various immunophenotypic markers have been introduced to aid in this process. A monoclonal antibody directed at a 15-kilodalton (kd) gross cystic disease fluid protein (GCDFP-15) was applied immunohistochemically to paraffin sections of 105 breast cancers and 585 nonmammary malignancies in order to assess its value in this context. In addition, GCDFP-15 was compared with another putative mammary epithelial marker, alpha-lactalbumin (ALA), with respect to sensitivity and specificity for a diagnosis of breast carcinoma. Overall, the rates of specificity and sensitivity and the predictive value of a positive result for GCDFP-15 were 95%, 74%, and 74%, respectively. Corresponding statistical parameters for ALA were 50%, 50%, and 23%. A consistent congruency between the reactivity patterns of primary and metastatic breast cancers was noted for GCDFP-15 but not for ALA. Besides mammary carcinomas, the major tumor types that expressed GCDFP-15 were carcinomas of the salivary glands, sweat glands, and prostate. Since the latter three types of lesions are unlikely to be diagnosed as metastatic breast cancer, statistical indices were recalculated after exclusion of these three tumor types. Following this exclusion, the adjusted rate of specificity of GCDFP-15 and the predictive value of a positive result for a diagnosis of metastatic carcinoma of the breast were each 99%. In contrast, predictive parameters for ALA were not altered. These results show that GCDFP-15 is a specific marker for breast cancer and is superior to ALA in this respect.

Immunohistochemical demonstration of epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), and keratin on mammary and extramammary Paget's disease

We examined the presence and the distribution of epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), and keratin in 4 cases (6 specimens) of mammary Paget's disease and 9 cases (18 specimens) of extramammary Paget's disease utilizing immunoperoxidase technique. Paget's cells in 23 out of 24 specimens were demonstrable for EMA. Positive staining was observed for CEA in every specimen. Among the 24 specimens, 16 showed positivity for keratin. In addition, CEA was positive in Paget's cells and the staining for CEA was stronger than that of EMA and keratin. On the other hand, some Paget's cells were negative for EMA of keratin although other positive cells were observed in the same sections. This findings indicates that Paget's cells might express CEA and/or EMA and/or keratin depending on their differentiation. EMA is present in most organs showing glandular differentiation, and anti-keratin antibody used in this study recognizes not only keratinocytes but glandular cells. Thus, our study suggests Paget's cells are of glandular origin.

Lack of beta-casein production by human breast tumours revealed by monoclonal antibodies

An immunohistochemical study with four monoclonal antibodies to human beta-casein was carried out to examine the expression of this milk protein in a wide range of normal tissues, in 127 breast tumours and in a heterogeneous panel of 42 malignancies of other histogenesis. The only normal tissue stained positively by the antibodies was the mammary gland in late pregnancy, during lactation and in the post-lactational regression period. None of the tumours of non-mammary origin showed any staining. Furthermore, only two of 40 benign breast lesions and one anaplastic primary carcinoma with its metastasis (among 87 breast carcinomas) showed any reactivity. The immunohistochemical results were supported by immunoblotting data and suggested beta-casein expression has no role to play as a marker in the diagnosis or monitoring of human breast cancer.

Tumor-associated antigens in breast carcinomas. Prognostic significance

In an attempt to identify biologic markers that might predict prognosis in breast cancer patients, the presence or absence of seven tumor-associated antigens in 54 infiltrating breast carcinomas was correlated with tumor recurrence rates (minimum five-year follow-up), axillary lymph node metastases and tumor volume. Immunohistochemical kappa-casein was present in 30 (56%) tumors, alpha-lactalbumin in 39 (72%) tumors, secretory component of IgA in 26 (48%) tumors, carcinoembryonic antigen in 34 (63%) tumors, pregnancy-specific beta-1-glycoprotein in 7 (13%) tumors, beta subunit of human chorionic gonadotrophin in 1 (2%) tumor and human placental lactogen in 0 (0%) tumors. There was no significant correlation between the presence or absence in tumor of any of the antigens, and prognosis as assessed either by 5-year recurrence rates (P greater than 0.18) or by the presence of axillary lymph node metastases (P greater than 0.20). No significant difference was noted in mean tumor volume (cm3) +/- SEM, between tumors with or without antigen immunoreactivity (P greater than 0.05).

Transferrin receptor (TrfR) expression in breast carcinoma and its possible relationship to prognosis. An immunohistochemical study

TrfR, a primitive membrane protein was demonstrated by immunohistochemistry in 87.6% of 105 cases of breast carcinoma, predominantly on the cell surface and in a strong and rather uniform pattern. Sporadic staining in a patchy fashion was observed. No difference between individual tumour types was seen, neither in cytomorphological staining pattern nor in staining intensity. Exceptionally, mucoid carcinomas showed weaker intensity for receptor expression. Because of the heterogenous expression of TrfR within most of the tumours the extent of staining reaction was determined by semiquantitative grading (low, moderate, high). These results were compared with grade of anaplasia, tumour staging and nodal status of the axilla. The extent of immunoreactivity revealed significant correlation with grade of anaplasia, whereas no correlation was found with staging and status of axillary lymph nodes. Tumours with higher degree of malignancy (GII-GIII) showed a higher extent of staining. The presence of TrfR in a high degree of expression thus implies some prognostic value. Its quantitative determination can provide kinetic data on the neoplasm.

Monoclonal antibodies to human casein

Two monoclonal antibodies, LICR-LON-32.2 (32.2) and LICR-LON-14.1 (14.1), are described which react with human casein. 32.2 reacts with human beta-casein and 14.1 with human kappa-casein. 32.2 also reacts with rat band 2 casein and bovine beta-casein, but 14.1 appears to be specific for human kappa-casein. These monoclonal antibodies do not cross-react with other milk proteins.

Kappa casein, lactalbumin and GCDFP 70 localization in human breast carcinomas: an immunohistochemical study using the avidin-biotin-peroxidase complex method

A retrospective study of 67 human breast carcinomas of various types and grades was conducted using the avidin-biotin-peroxidase complex (ABC) to localize casein, lactalbumin, and GCDFP 70 on paraffin sections. Estrogen and progesteron receptors also were evaluated. This study demonstrated the following: (1) Casein positive cells were present in all cases with a variable distribution and degree of staining, whereas lactalbumin and GCDFP 70 were seen in only 40 and 43% of the cases, respectively. (2) No significant relationship was observed between casein, lactalbumin, GCDFP 70 and the histologic types of tumors or the extent of stromal elastosis, with the exception GCDFP 70, which was observed more often in well-differentiated ductal carcinomas. (3) No significance was established in the relationship between antigens and steroid receptor content, with the exception of casein; strong casein immunostaining was significantly related to high progestin receptor levels. (4) Lactalbumin and GCDFP 70 were significantly associated with each other, but independently so of the histologic grades and types, the extent of stromal elastosis, and the steroid receptor content of the tumor cells.

Tumour-associated antigens in mammary and extramammary Paget's disease

The immunoperoxidase technique was used to study the immunoreactivities of two murine monoclonal antibodies to carcinoma-associated antigens raised respectively against a human breast cancer line (MBr1) and an ovarian carcinoma (MOv2) and of a conventional anti-CEA serum in 20 cases of mammary Paget's disease of the nipple and in three cases of extramammary Paget's disease. Each of the immunoreagents stained Paget's cells in a high proportion of cases and failed to discriminate mammary from extramammary disease. The antigenic phenotypes of underlying in situ or infiltrating breast carcinomas corresponded to those of the associated Paget's disease of the nipple. The consistent immunoreactivity of eccrine and apocrine sweat glands and of normal mammary epithelia indicated an antigenic relationship between epithelia of adnexal derivation and Paget's cells.

Immunohistochemical study of mammary and extra-mammary Paget's disease

Paraffin sections of 13 cases of Paget's disease (six mammary and seven extra-mammary) were investigated with mono- and polyclonal anti-carcinoembryonic antigen (CEA) and with monoclonal anti-human milk fat globule membrane antigen (HMFG). One of these cases was also analysed in cryostat sections with monoclonal anti-cytokeratin and anti-keratin. Three immunohistochemical labelling patterns were identified: (I) All six cases of mammary Paget's disease were positive for anti-HMFG and negative with monoclonal anti-CEA (although they stained to a variable degree with polyclonal anti-CEA). (2) Two cases of extra-mammary Paget's disease (both anal location) were positive with monoclonal anti-CEA and only weakly stained for HMFG suggesting epidermal spread from a colo-rectal carcinoma. (3) The other five cases of extra-mammary Paget's disease were negative or weakly stained for CEA and positive for HMFG. We speculate that this group of cases represents epidermotropic eccrine carcinoma. The immunohistochemical use of monoclonal anti-HMFG and -CEA is helpful in the diagnosis of Paget's disease; moreover it gives information about the origin of the primary tumour.

Juvenile milk protein secreting carcinoma

A case of juvenile secretory carcinoma of the breast is reported. The tumor occurred in a 19 yr-old nulliparous woman and was treated by local resection; it recurred 7 years later. Slight infiltration of the pectoral muscle, metastatic involvement of one lymph node and multifocal areas of carcinoma were found at radical mastectomy. No further recurrence has been detected after 1 year. This case confirms the slow evolution of this neoplasm but stresses that its behavior is not always as indolent as previously believed. We have used histochemical techniques for mucins (PAS, Alcian Blue) and immunoperoxidase methods for milk proteins (MFGM, beta-Casein, alpha-lactalbumin), for myoepithelial cells (actin) and for oncofetal antigens (CEA). Our results suggest that: Immunoperoxidase methods for milk proteins are a more specific and reliable marker than PAS staining in characterizing the secretory activity of juvenile carcinoma. The absence of myoepithelial cells in infiltrative areas detected by immunoperoxidase methods for actin confirms the low degree of organization in this well differentiated carcinoma of limited aggressiveness which secretes milk proteins.

Similarities of antisera to casein and epithelial membrane antigen

Antisera raised against human milk fat globule membranes and against the casein fraction of human milk have been compared. Using an immunohistochemical stain of tissue sections it has been shown that many of the antigenic determinants detected by the different antisera are identical. A radioimmunoassay for epithelial membrane antigen (EMA) showed that casein preparations are associated with small quantities of EMA. Antisera to casein frequently contained appreciable concentrations of antibodies to EMA and this accounts for the immunohistochemical staining of non-mammary tissues.

Immunocytochemical detection of tumour markers in bone metastases from carcinoma of the breast

The value of immunocytochemical methods for detecting seven tumour-associated antigens was assessed in ten cases of bone metastases from carcinoma of the breast. In order to obtain the optimal preservation of both their structure and antigenicity, the biopsies were fixed-decalcified in Bouin's fluid by means of an apparatus based on ion-exchange resins recently developed in this laboratory. Of the different tumour markers, milk fat globule membrane antigen and carcino-embryonic antigen were found to be present in the majority of the cases of neoplastic cells. These two markers appear, therefore, to be the most useful for the immunocytochemical identification of metastatic neoplastic cells in the bone marrow originating from carcinoma of the breast.

Medullary carcinoma of breast: an immunohistochemical study of its lymphoid stroma

Immunoperoxidase staining for IgA, IgG, IgM, and secretory component (SC) was performed on ten cases each of medullary carcinoma and infiltrating duct carcinoma of breast. Plasma cell-rich stroma of medullary carcinoma was found to contain predominantly IgA plasma cells. Tumor cells also contained IgA and SC. In contrast, the few plasma cells of infiltrating duct carcinoma were found to be predominantly IgG type, and the tumor cells contained none or very small amounts of IgA and SC. Because the presence of IgA plasma cells and IgA and SC in lining epithelial cells are characteristic features of organs of the secretory Ig system, these findings in medullary carcinoma may suggest a good degree of functional differentiation of these tumor cells and correlate well with the well-known favorable prognosis associated with this tumor.

Detection of alpha-lactalbumin in breast lesions and relationship to estrogen receptors and serum prolactin

Alpha-lactalbumin, the B protein of lactose synthetase secreted by the mammary epithelial cells, was isolated and purified from fresh human milk and injected into rabbits for antibody production. Indirect immunofluorescence (IIF) was done on various types of breast lesions to assess the relationship, if any, between histologic type and production of alpha-lactalbumin. Fifty percent of fibroadenomas and fibrocystic disease and 63% of infiltrating ductal carcinoma showed positive reaction. No false positives were found on IIF of alpha-lactalbumin of several tumors of nonmammary tissue. These findings suggest that IIF for alpha-lactalbumin may be helpful in ascertaining the site of origin of metastatic breast tumors. However, serum alpha-lactalbumin was detected by radioimmunoassay in only 10% of women with infiltrating ductal carcinoma, indicating that this may not be a useful marker for the presence of breast cancer at least by the method employed. This discrepancy between serum and tissue alpha-lactalbumin may be due to the short half-life of serum alpha-lactalbumin or to the lack of secretion of the protein into the blood. There was no apparent relationship between the presence of estrogen receptors or serum prolactin and alpha-lactalbumin in the 27 mammary carcinomas investigated.

The demonstration of alpha lactalbumin in human breast carcinomas

Alpha lactalbumin, a good marker of functional differentiation, has been demonstrated in 51 of a 100 human breast carcinomas examined using the immunoperoxidase technique. There is no relationship between production of alpha lactalbumin and histological differentiation, and the absence or presence of lymph-node metastases.

Tubular carcinoma: a variant of secretory breast carcinoma

Fifteen cases of tubular carcinoma of the breast have been studied using histochemical methods for mucosubstances, immunocytochemical methods for casein and actin and conventional electron microscopy. Mucosubstances and casein were demonstrated lying freely in the lumina of the tubules. Occasionally, mucosubstances and casein assumed the form of target-like intracytoplasmic 'inclusions' like those characteristically seen in lobular carcinoma. The neoplastic cells did not react with antisera specific against actin. Even at ultrastructural level no myoepithelial cells were observed, whilst villi were revealed along the tubular luminal surface. It appears that, in addition to distinctive biological, histological and ultrastructural features, tubular carcinoma has an almost constant histochemical pattern. This suggests a differentiation towards epithelial secretory cells engaged in intensive milk protein production which has also been shown to be a feature of lobular carcinoma. It is concluded that though lobular carcinoma and tubular carcinoma of the breast have been traditionally regarded as two distinct entities, they have certain similar functional characteristics and it is postulated that these two tumours could represent the extreme variants fo the same entity: the infiltrative lobular carcinoma being the most undifferentiated and tubular carcinoma the most highly differentiated.

The identification of 'casein' in human breast cancer

A retrospective study of ninety-six cases of breast cancer was carried out to determine the prognostic values of a casein immunolocalization technique. This was performed using an indirect immunofluorescence method with antisera raised in rabbits to pooled human casein. Fluorescence positivity was graded according to its intensity and distribution. The pathology of each tumour was studied and the tumour type, histological grade and tissue response assessed. The relationship between these observations and the casein content of the tumour was studied. In addition the correlation between casein content and age, menopausal state, clinical staging and survival was investigated. The incidence of casein positivity in our series was 50% with approximately half of the positive cases showing strong fluorescence. There was a relationship between casein content and the age of the patients, with casein being more frequently found in tumours from younger patients. Tumours with a high casein content, in general, show a poorer survival than the group as a whole. This difference in survival was most marked in the first eight years after operation and restricted to those tumours in clinical stage I and histological grade I. The presence of casein in the tumours did not appear to be related to the other factors examined.

Carcinoembryonic antigen and other tumor markers in tissue and serum or plasma of patients with primary mammary carcinoma

50 patients with primary breast cancer were studied to determine the CEA and HCG contents in their tumor cells before any treatment was initiated. Tumor cells were obtained by needle biopsy and each tumor cell population was stained by immunofluorescence. In 21 of the 50 patients, CEA containing cells were found in a frequency ranging from 5 to 80% of the tumor cell population. The results were confirmed by radioimmunoassay of tumor extracts. No apparent relation was seen to cytologic type or grade of differentiation. HCG was detected by IF in 4 tumors with an apocrine cytologic cell type. The level of CEA in plasma was determined before treatment and followed for 2-6 months in 72 patients. CEA was the only measured serum parameter that correlated initially with size and extent of the localized tumor. It was too low to be of use for monitoring primary disease, but should be of value in early detection of metastasis. Posttreatment a low or decreased plasma CEA was seen more often in patients who had had curative treatment than in those given palliative radiation. No raised serum HCG levels were found. Raised serum liver enzymes did not predict the extent of the primary tumor but may be an indication of distant spread. Tumor CEA content and CEA plasma concentration were correlated, although not very strongly. This means that CEA, although present in the tumor, is not always released in measurable amounts.

Immunofluorescence studies on formalin-fixed and paraffin-embedded material

In an attempt to apply immunomorphologic techniques to formalin-fixed material, various tissues were studied by indirect immunofluorescence. To minimize nonspecific background staining, formalin-fixed paraffin sections were treated with pronase prior to incubation with the antisera. This technique was published by Huang in 1975 to study hepatitis B core and surface antigen in formalin-fixed liver-tissue. Our examination demonstrate that this technique might enable the morphologist to identify immunoglobulins in formalin-fixed tissues and so to get new criteria for their diagnosis.

Morpho-functional differentiation in lobular carcinoma of the breast

Lobular carcinoma of the breast has been studied using histochemical methods for mucosubstances; immunocytochemical methods for casein and actin; the ruthenium red electronycytochemical method for acid glycoproteins and an immunoelectroncytochemical method for casein. Mucosubstances and casein showed a similar cytoplasmic localization, but casein production was much more intense and also showed a more diffuse cytoplasmic localization. Occasionally casein assumed the form of target-like 'inclusions' as seen characteristically with the mucosubstances. The neoplastic cells were not stained by antisera against actin. Ultrastructurally, some cells showed an intracytoplasmic lumen with microvilli and/or an irregular outline at one extremity which was covered by microvilli. An electron-dense 'fuzz' and casein coated the microvilli of cells exposed respectively to ruthenium red and an anticasein serum followed by peroxidase--anti-peroxidase complexes. It is concluded that lobular carcinoma shows evidence of epithelial rather than myoepithelial differentiation with the emphasis on epithelial secretory cells engaged in intensive milk protein production. All 10 tumours tested for oestrogen receptors were positive in contradistinction to ductal carcinoma with a lower incidence of positivity. It appears that, in addition to distinctive histological and histochemical features, lobular carcinoma has an almost constant endocrine pattern in respect of its oestrogen receptor content.

[Immunofluorescence studies of experimental glomerulonephritis in formalin-fixed and paraffin-embedded material (author's transl)]

Immunofluorescence studies are an essential part of the diagnosis in glomerulonephritis. For these studies unfixed, frozen material was used only, on account of intense background staining of formalin-fixed slides. A method developed by Huang (1975) was tested on experimental glomerulonephritis. He succeeded in minimizing the background staining of formalin-fixed liver tissue with pronase-treatment. Our results show no differences in the immunofluorescence of the experimental glomerulonephritis between frozen and paraffin-embedded sections. It seems to be possible therefore to investigate a glomerulonephritis in formalin-fixed material by this method.

Immunofluorescence studies on pathologic routine material: application to malignant lymphomas

In an attempt to apply immunmorphologic techniques to pathologic routine material, malignant lymphomas of the Non-Hodgkin- and the Hodgkin-type were studied by indirect immunofluorescence. To minimize nonspecific background staining formalin fixed paraffin sections were treated with protease prior to incubation with the antisera. The usefullness of this procedure in providing additional diagnostic criteria was tested on specimens of malignant lymphomas (chronic lymphocytic leukemias, immunocytic lymphomas, plasmocytic lymphomas, centrocytic lymphomas, centroblastic-centrocyctic lymphomas, centroblastic lymphomas, immunoblastic lymphomas, lymphoblastic lymphomas of Burkitt, convoluted and unclassified type, Hodgkin's disease). In addition, cases of nonspecific lymphadenitis were studied. The discrimination of single cells particularly of the B-cell line was facilitated using immunofluorescence and different patterns were easily recognized thus aiding the diagnosis based on light microscopic criteria. In addition, preliminary evidence was obtained that lymphoblastic lymphomas categorized as "others" may be further characterized.