The detection of intracellular antigens in human leucocytes by immunoperoxidase staining

Immunocytochemical Labelling of Haematological Samples Using Monoclonal Antibodies

I reflect on my experience working with David Y. Mason in the Leukaemia Research Laboratories in the Nuffield Department of Pathology at the University of Oxford in the early 1980s. This was soon after the first monoclonal antibodies had been produced, which led to an exciting and productive time in biological discovery and pathology diagnostics. A specific focus in the laboratory was the development of immunoenzymatic staining methods that would enable monoclonal antibodies to be applied in diagnostic practice. This paper describes the work that led to the performance of immuno-alkaline phosphatase staining on blood and bone marrow smears, the success of which changed leukaemia diagnosis.

Morphologic, Immunologic, and Cytogenetic Characteristics of Secondary Acute Unclassifiable Leukemia in Hodgkin's Disease

Blast cells from five cases of secondary unclassifiable leukemia following therapy for Hodgkin's disease were studied by cytochemical, immunological and cytogenetic analyses. Cytochemical and immunological reactivity were in accordance with poorly differentiated, myeloid blasts. The four cases in which karyotype analysis was performed showed specific chromosomal abnormalities. No evidence of multiple lineage involvement was found. Problems in classifying these cases of secondary ANLL were due to the high grade of undifferentiation of the blast cells. Their low cytochemical reactivity with markers of myeloid differentiation was similar to what may be observed in patients with acute undifferentiated leukemia or with chronic myeloid leukemia in blast crisis.

Intracytoplasmic Lysozyme in Malignant Hematologic Disorders: An Immunoperoxidase Study

Intracytoplasmic lysozynie was studied by the peroxidase antiperoxidase (PAP) and protein A-peroxidase methods in 130 cases of various myeloproliferative and lymphoproliferative disorders and 21 lymph nodes and bone marrow metastases from solid primary tumors. This marker, which can be identified in formalin or Zenker-fixed tissues, as well as in peripheral blood and bone marrow smears, proved useful to distinguish malignant myeloid and histiocytic tumors from malignant lymphoid and undifferentiated epithelial metastases. The diagnostic application of these findings are discussed.

Analysis of the Germinal Center Reaction in Tissue Sections

Germinal centers are short-lived microanatomical compartments with essential roles in adaptive immunity. These lymphoid structures can be identified in secondary lymphoid organs using both flow cytometry and immunohistological analyses, but only the latter provides useful architectural and spatial information. Here we describe how to use immunofluorescence and immunohistochemistry with specific antibodies to precisely highlight the cellular and architectural features of germinal centers, both in human and mouse secondary lymphoid organs, and to study their normal development and disturbance in disease.

Lactoferrin in human neutrophilic polymorphonuclear leukocytes in relation to iron metabolism

Lactoferrin (LF), the iron-binding protein of external secretions and neutrophilic polymorphonuclear leukocytes (PMN), was studied in 27 patients during granulocytosis caused by acute inflammation and in disorders without granulocytosis (iron deficiency anemia, iron overload and liver diseases). During granulocytosis the LF concentration of PMN was significantly lower than in controls (p less than 0.001). This difference proved to be related to the number of PMN. A relation between the LF concentration of PMN and iron metabolism could be demonstrated: loss of iron by blood donation is accompanied by a significant decrease in the LF concentration in PMN, whereas iron therapy in patients with iron deficiency anemia is accompanied by a significant increase in the LF concentration in PMN.

Fetal cell identifiers: results of microscope slide-based immunocytochemical studies as a function of gestational age and abnormality

OBJECTIVE

We evaluated monoclonal antibodies to 3 cell surface and 3 intracellular antigens for their relative usefulness as markers to identify fetal cells in maternal blood.

STUDY DESIGN

With indirect immunocytochemical labeling techniques, antigen expression was studied in 52 fetal blood samples as a function of gestational age, fetal karyotype, the presence of multiple anomalies detectable on ultrasonography, and anemia.

RESULTS

A decline in the expression of these antigens as gestational age advanced was demonstrated. Samples from karyotypically abnormal fetuses, fetuses with multiple anomalies, and anemic fetuses showed an antigenic distribution that was immature for gestational age. In normal fetuses zeta globin and epsilon globin expression decreased after 12 to 14 weeks, potentially limiting the utility of these proteins as fetal cell markers in the isolation of fetal cells from maternal blood.

CONCLUSIONS

The results of this study demonstrate a fetal developmental hematologic profile that varies with gestational age and also with pathologic condition. Antibodies to the gamma chain of fetal hemoglobin and the transferrin receptor (CD71) are the most useful fetal cell-identifying reagents.

The status of immunohistochemical studies in lymphoma diagnosis

Immunohistochemical studies of formalin fixed paraffin embedded sections today constitute an essential component of the diagnostic process for malignant lymphoma. Lineage related markers are of value in distinguishing various lymphomas from anaplastic large and small cell carcinomas, and from sarcomas. Other more recently available markers are of value in establishing prognosis and, on occasion, in differentiating between neoplastic and reactive proliferations. Meticulous attention to reagent control and technical procedures is essential to all such studies.

Molecular cloning of a novel myeloid granule protein

Granulocytes are recognized by the presence of granules, including primary (azurophilic) and secondary types. Each granule type contains distinct and characteristic families of enzymes. We have screened a murine bone marrow cDNA library to obtain a series of sequences corresponding to mRNAs which are both myeloid-specific and appear to be expressed only in immature bone marrow cells. A 1,160 bp sequence (B9) has been isolated, which shows restricted expression in murine bone marrow, with the highest levels in cultures enriched for promyelocytes. Translation yields a single open reading frame of 167 amino acids and a calculated MW of 19.33 kd. A single potential N-glycosylation site is present. Evaluation of the amino terminal sequence shows 2 polar amino acids flanking a hydrophobic region, suggesting a signal sequence and the possibility of post-translational modification. An extensive search of the protein data base reveals 30% identity over 90 amino acids with porcine cathelin, a cystatin-like cysteine proteinase inhibitor. This sequence identity includes conservation of the 4 cysteine residues noted in all members of the cystatin superfamily. In an attempt to further characterize this novel sequence, a polyclonal antiserum was prepared by immunization with a 20 amino acid synthetic peptide corresponding to a unique portion of the carboxy terminus. Immunoelectron microscopy localized B9 to neutrophilic granules. We have identified a novel myeloid-specific granule protein related to porcine cathelin, but showing important structural differences. This may represent the first isolated member of a new cystatin family. More importantly, the small size of the B9 gene and its tight pattern of early expression make B9 an excellent reporter molecule for the study of new factors important in myeloid differentiation.

Distinct lysozyme content in different subtypes of acute myeloid leukaemic cells: an ultrastructural immunogold study

Using an ultrastructural immunogold method, we performed a quantitative study on cellular lysozyme (LZ) content in young normal bone marrow cells and in 14 cases of acute myeloid leukaemia (AML) of the M2, M3, M4 and M5 types. In five cases of M2 we found significantly lower LZ content than in normal promyelocytes and than in nine cases of M3, M4 and M5. In M3, M4 and M5 cells a very high LZ content was observed whereas the serum LZ activity was high in M4 and M5 and normal in M3. The intragranular LZ content was especially high in M5 and in most granules of M4 cells. The immunogold reaction (IGR) for LZ was also performed in cells previously reacted for myeloperoxidase (MPO). In M2 the granules showed definite positive MPO reactivity and low LZ density (granulocytic pattern), whereas in M5 we found high granular LZ content and weak or almost negative MPO activity (monocytic pattern). In M4 we found 'granulocytic' and 'monocytic' type of granules in the same cell. The IGR for LZ performed in post-embedded M5 cells which were previously subjected to phagocytosis of latex particles, showed granules that had moved toward the phagosome, releasing LZ without degranulation. The above findings and those showing normal serum LZ in M3 despite their high cellular LZ content, definitely indicate that only leukaemic M4 and M5 cells secrete LZ into their environment, explaining the high serum LZ observed in those leukaemias.

Characterization of the mononuclear infiltrate involved in regression of halo nevi

Halo nevi are characterized by progressive degeneration of nevus cells surrounded by a mononuclear cell infiltrate. We studied the morphological features of the nevus cells and the composition of the mononuclear cell infiltrate in 15 cases of halo nevi using immunohistochemical techniques and a battery of antibodies to different subsets of lymphocytes and histiocytes. Regression could be divided into four more or less identifiable stages, associated with different subsets of lymphocytes and monocyte-macrophage lineage cells. Stage I (preregression): nests of unremarkable nevus cells were surrounded by a moderate number of T lymphocytes (relatively small percentage of helper inducer T cells), occasional B cells and macrophages. Stage II (early regression): large number of T lymphocytes and FXIIIa-positive cells were in close contact with nevus cell clusters which showed ragged edges. Lysozyme-positive cells and epidermal Langerhans cells were mildly increased. Stage III (late regression): single nevomelanocytes showing mild atypia were present. Numerous T lymphocytes and macrophages positive for lysozyme, KP1 and/or FXIIIa were interspersed between the nevus cells. Increased numbers of epidermal Langerhans cells were present. Stage IV (complete regression): no nevus cells were observed and moderate numbers of T lymphocytes only remained. These results suggest that T cells, especially T-suppressor cells, and different subsets of macrophages participate in the regression of the nevi.

Mantle zone lymphoma: an immunohistologic study of skin lesions

BACKGROUND

Mantle zone lymphoma (MZL) is a B-cell proliferation regarded as the follicular variant of intermediate lymphocytic lymphoma (ILL). Neoplastic small lymphoid cells proliferate as wide mantles around atrophic centers of benign appearance.

OBJECTIVE

The clinical, histologic, and immunohistochemical features of four cases of MZL, heralded by cutaneous lesions, are described and correlated with the lymph node pattern.

RESULTS

All specimens showed extensive nodules in the reticular dermis invading the subcutaneous tissue. They were mainly composed of a proliferation of small lymphocytes with slightly irregular nuclear contours and clumped chromatin, forming wide mantles around small atrophic germinal centers. Serial biopsy specimens in case 1 revealed evolution of the skin lesions from pseudolymphoma into MZL. Their immunohistochemistry was similar to that of lymph nodes and showed that the neoplastic cells were CD5+, CD20+, CD22+, CD25+, CD74+, Leu-8+, HLA-DR+, IgM+, IgD+ with restriction for the lambda light chain, CD10-, and CD71-, whereas the germinal center cells were polyclonal. In three cases many CD38+, PCA-1+ plasma cells were present both in the grenz zone and in bordering neoplastic nodules. The clinical course was chronic. The only death occurred from unrelated causes; one patient is still alive 17 years after onset.

CONCLUSION

Skin lesions may be the only manifestation of MZL for an extended period. The differentiation between pseudolymphoma and other lymphoma subtypes is based not only on the histologic and cytologic features but also on the architecture, followed by immunohistochemical confirmation.

ZB51: a monoclonal antibody reactive with human plasma cells

Several monoclonal antibodies have been raised in the past which react with human plasma cells but they have all shown additional reactions with other cell types. In this paper we describe a new monoclonal antibody, ZB51, which recognizes an intracellular antigen in normal plasma cells in cryostat tissue sections and cell smears, and which also reacts with neoplastic cells in most cases of myeloma and with plasma cell lines. The antibody shows minimal reactivity with a few eosinophils and myelocytes in bone marrow and stains a myeloid cell line. Whilst normal epithelium is not labelled, antibody ZB51 stains two carcinoma cell lines. Although it was not possible to characterize the target antigen in terms of molecular weight, the reactivity of antibody ZB51 with normal and neoplastic plasma cells makes it a useful new immunocytochemical reagent.

Acid ethanol fixation and polyester wax embedding combines preservation of antigenic determinants with good morphology and enables simultaneous bromodeoxyuridine (BrdU) labeling

Lymphoid tissue, and/or isolated peripheral mononuclear blood cells were fixed in acid ethanol and embedded in polyester wax (melting point 37 C). The excellent cytomorphology obtained allowed distinguishing different types of individual lymphoid and nonlymphoid cells. Furthermore, this procedure was satisfactory in the immunophenotyping of histiocytes, endothelial, mesenchymal, epithelial cells, different (sub-) types of lymphocytes and also of lymphokine activated killer (LAK) cells. The staining patterns obtained with the different poly- and monoclonal antibodies on polyester wax sections were not only analogous to those obtained on frozen sections, but cells which had incorporated bromodeoxyuridine could be double labeled with specific antiserum.

Antigenic and catalytic disparity in the distribution of cytochrome P-450-dependent 25-hydroxyvitamin D3-1 alpha- and 24-hydroxylases

Chick 25-hydroxyvitamin D3-1 alpha-hydroxylase, a cytochrome P-450 monooxygenase with a molecular weight of 57 kDa, can be isolated as described by Mandel et al. (1990 b). Under normal physiological circumstances, it occurs exclusively in kidney mitochondria. An isozyme of the 1 alpha-hydroxylase, known as the 24-hydroxylase, which uses the same substrate to yield an isomeric product, is also a cytochrome P-450 monooxygenase, has a molecular weight of 55 kDa, and like-wise occurs in kidney mitochondria. The amino-terminal sequences of the first 10 residues of the two isozymes are 100% homologous. Monoclonal antibodies of the IgM class raised against the 1 alpha-hydroxylase, which quantitatively discriminate against other P-450 cytochromes of mitochondrial or microsomal origin, recognize and interact with the 24-hydroxylase as an antigen. In the present study we show that the intestine, which is the only non-renal tissue with demonstrable 24-hydroxylase activity, gives a positive peroxidase-antiperoxidase immunohistochemical reaction using the monoclonal antibodies against the 1 alpha-hydroxylase. The reactions revealed that the antigen in the kidney is restricted to the cortical proximal tubular cells while in the intestine, the antigen is localized in the enterocytes of the villi. In kidney medullary or intestinal crypt cells, or in liver, heart and lung tissues where 1 alpha-hydroxylase or 24-hydroxylase activity could not be detected using cell or tissue homogenates, the immunohistochemical reactions were also negative.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute myelogenous leukemia with leukemia cutis. Eighteen cases seen between 1969 and 1986

Leukemia cutis was documented by biopsy in 18 of 877 patients (2%) with acute myelogenous leukemia (AML) seen at Roswell Park Memorial Institute (Buffalo, NY) between 1969 and 1986. French-American-British (FAB) types included four M2, one M3, ten M4, and three M5. Lysozyme was more consistently detectable in skin sections in our cases than Leu-M1, alpha-1-antitrypsin, alpha-1-antichymotrypsin, or chloroacetate esterase activity. Additional extramedullary sites of involvement were present in 16 patients, including meningeal leukemia in six. Two patients had leukemia cutis preceding bone marrow leukemia. Skin was the initial site of relapse in 11 patients, without marrow relapse, occurring as late as 5.5 years after diagnosis. Most patients in this retrospective series were treated with radiation therapy and/or palliative chemotherapy, and did poorly, with prompt bone marrow relapses and serial skin relapses. Long-term disease-free survival was achieved in the one patient whose skin relapse was treated with whole-body electron-beam radiation therapy in conjunction with reinduction and consolidation chemotherapy. Severe skin toxicity was caused by administration of Adriamycin (doxorubicin) 12 days after electron-beam irradiation in one patient, but was not seen when cytosine arabinoside was administered in doses up to 3 g/m2 in conjunction with radiation therapy. This retrospective review suggests that optimal management of AML involving skin might include whole-body electron-beam irradiation in conjunction with induction or reinduction chemotherapy without anthracyclines, followed by consolidation chemotherapy. Additionally, there should be ongoing surveillance for and treatment of extramedullary disease at other sites, including the meninges.

Expression of the neutrophil elastase gene during human bone marrow cell differentiation

Neutrophil elastase, a potent serine protease carried and released by activated neutrophils, is not synthesized by neutrophils, but by their bone marrow precursor cells. Using in situ hybridization with 35S-labeled antisense and sense neutrophil elastase cRNA probes, the present study demonstrates that expression of the neutrophil elastase gene is tightly controlled in bone marrow precursors and occurs during a very limited stage of differentiation of the neutrophil myeloid series, almost entirely at the promyelocyte stage. Neutrophil elastase mRNA transcript levels are detectable to a limited extent in blasts, increase markedly in the promyelocyte stage, and then disappear as promyelocytes further differentiate. Control probes specific for myeloperoxidase, lactoferrin, and beta-globin mRNA transcripts, respectively, demonstrated contrasting gene expression. Myeloperoxidase mRNA transcripts were also found almost exclusively at the promyelocyte stage, but myeloperoxidase mRNA levels disappeared earlier than do neutrophil elastase mRNA levels, suggesting that expression of these genes may be differently controlled. In comparison, lactoferrin mRNA transcripts were detected late in the neutrophil lineage, while beta-globin mRNA was detected only in cells of the erythroid lineage. Together these observations suggest that the expression of the neutrophil elastase gene is likely under very tight control, and is likely different than that for other constituents of the neutrophil granules.

Use of light microscopic immunotechniques in selecting preparation conditions and immunoprobes for ultrastructural immunolabelling of lactoferrin

Successful postembedding immunolabelling for electron microscopy is sometimes difficult to achieve. We propose that light microscopy can be used (1) to detect quickly processing steps which have an adverse effect on the tissue antigenicity and (2) to check the specific reactivity of the immunogold detecting system normally employed at the ultrastructural level. The individual steps of fixation, dehydration and embedding were tested for their ability to preserve antigenicity by light microscopic peroxidase--anti-peroxidase cytochemistry. Steps that severely reduced antigenicity were replaced by less destructive alternatives compatible with reasonable ultrastructural preservation. The specific reactivity of the immunogold detecting system was assessed by using the light microscopic immunogold-silver staining method. We studied the antigen lactoferrin in human neutrophilic granulocytes from patients with chronic myeloid leukaemia. We obtained strong immunolabelling of specific granules and good ultrastructural preservation using routine methods at room temperature. For lactoferrin the method of choice was to fix in 3% paraformaldehyde/0.1% glutaraldehyde followed by 1% OsO4, dehydrate in 70% ethanol, embed in LR White resin and polymerize at 40 degrees C for 40 h. These conditions may not be suitable for all antigens and we emphasize that for each new antigen a similar study should be carried out.

Use of monoclonal antibody against human neutrophil elastase in normal and leukaemic myeloid cells

A monoclonal antibody, NP57, was produced and used against the neutrophil granule protein elastase, which selectively stain neutrophils in cryostat and paraffin wax sections. The antibody stains neutrophils and a subpopulation of monocytes in blood smears and neutrophil precursors in bone marrow smears, and gives positive reactions with the cell lines HL60 and U-937. It labelled the blast cells in 68% of cases of acute myeloid leukaemia (M1-M5) but was unreactive with all cases of lymphoid leukaemias. Most of the elastase negative myeloid leukaemias were labelled by monoclonal anti-myeloperoxidase (antibody MPO-7) as were cells from the promyelocytic line HL60. No cases of myeloid leukaemia showed the opposite pattern--that is elastase positive, myeloperoxidase negative, suggesting that the production of myeloperoxidase precedes the onset of elastase synthesis during myeloid maturation. The anti-elastase antibody NP57 is a useful addition to the range of monoclonal antibodies available for the differential diagnosis of acute leukaemia by alkaline phosphatase-antialkaline phosphatase (APAAP) labelling of cell smears; it may also be of value for the histopathological diagnosis of tumour deposits in myeloid leukaemia and for the detection of neutrophils in paraffin sections.

Immunocytochemical analysis of immunoglobulin-containing cells in CSF and blood in inflammatory disorders of the central nervous system

Cells containing immunoglobulins G, A, and M were evaluated in paired cerebrospinal fluid (CSF) and peripheral blood (PB) samples. These were obtained from 12 patients with bacterial meningitis, 14 patients with viral meningitis, 6 cases of lymphocytic meningoradiculitis (LMR), 10 cases of multiple sclerosis (MS), 6 cases of herpes zoster ganglionitis and 27 patients with non-infectious disorders of the CNS. PB cells from 20 healthy donors served as controls. Using alkaline phosphatase (AP)-conjugated antibodies to human immunoglobulin (Ig) G, A, and M in a carrageenan solution it was possible to demonstrate repeatedly intracytoplasmic Igs over more than 1 year without any detectable loss of specificity and staining intensity. Immunoglobulin-containing cells (ICC) could be detected in the CSF of 96% of patients with inflammatory diseases of the central nervous system (CNS) or with MS but not in the control cases.

Synthesis of functional bovine opsin in insect cells under control of the baculovirus polyhedrin promoter

In vitro expression of cDNA encoding bovine opsin is accomplished using the baculovirus expression vector system. Full-length opsin was synthesized which was recognized by poly- and monoclonal antisera raised against bovine rhodopsin. Upon infection with a recombinant virus, 1 x 10(6) insect cells produced up to 3 micrograms opsin. Incubation of the in vitro synthesized opsin with 11-cis retinal produced a hydroxylamine-stable, photosensitive pigment.

Abnormal neutrophils in acute myeloid leukemia and myelodysplastic syndrome

Neutrophils and band forms from patients with acute myeloid leukemia and myelodysplastic syndrome were stained for the presence of myeloperoxidase using a cytochemical method (diaminobenzidine/hydrogen peroxide) and the alkaline phosphatase--anti-alkaline phosphatase immunocytochemical procedure (using monoclonal anti-myeloperoxidase). Neutrophils and bands were also stained for elastase and lactoferrin using monoclonal and polyclonal antibodies, respectively. Subpopulations of neutrophils and bands from cases of acute myeloid leukemia and myelodysplasia exhibited a qualitative and/or quantitative deficiency in myeloperoxidase. In addition, a quantitative decrease in elastase and/or lactoferrin staining was detected. Thus, neutrophils and bands from patients with acute myeloid leukemia and myelodysplastic syndrome have a defect in one or more of the constituents of primary and/or secondary granules. These defects are consistent with the view that abnormal neutrophils and bands are derived from a malignant clone of myeloid precursor cells.

Immunophenotyping of acute myeloid leukemia by immuno-alkaline phosphatase (APAAP) labeling with a panel of antibodies

A panel of eight antibodies was used by the alkaline-phosphatase/anti-alkaline phosphatase (APAAP) method to stain peripheral blood films, bone marrow smears, and cytocentrifuge preparations from 29 cases of acute myeloid leukemia. These findings were correlated with the French-American-British (FAB) classification. Leukemic cells from six cases of myeloblastic leukemia (FAB;M1) were predominantly labeled by the antimyeloperoxidase monoclonal antibody (MPO-7). Leukemic cells from the majority of eight cases of myeloblastic leukemia with maturation (FAB;M2) and progranulocytic leukemia (FAB;M3) stained with monoclonal antibodies MPO-7, NP57 (anti-elastase), and EBM11 (antimonocyte/macrophage). Leukemic cells from six cases of myelomonocytic (FAB;M4) and five cases of monocytic (FAB;M5) leukemia were most often labeled with antibodies MPO-7, NP57, and EBM11 as well as monoclonal antibodies Y1/82A (anti-monocyte) and KB90 (against the p150, 95 molecule, CD11c; a monocyte/granulocyte marker), but not with monoclonal antibody C17 (antiglycoprotein IIb/IIIa) and/or monoclonal antibody Y2/51 (antiglycoprotein IIIa). Erythroblasts from a single case of erythroleukemia (FAB;M6) were not labeled with any of the antibodies from this panel. Leukemic cells from two cases of acute megakaryocytic leukemia (FAB;M7) stained strongly with the monoclonal antiglycoprotein IIIa/IIb antibody (C17) and antiglycoprotein IIIa antibody (Y2/51). Staining by the APAAP method with this panel of antibodies was easy to perform, required no expensive instrumentation, and provided useful information in the classification of acute myeloid leukemia.

Single-cell immuno-beta-galactosidase staining of heterogeneous populations. Practical application on limited cell numbers

In this paper we describe a sensitive immunocytochemical staining method, particularly useful for the study of subpopulations of cells in complex mixtures such as bone marrow cell suspensions. E. coli beta-galactosidase is used as a label, which has the advantage that no endogenous activity is observed under the present experimental conditions. Direct sedimentation of cells on to poly-L-lysine-pretreated multi-well slides followed by gentle fixation prevents cell loss during preparation and subsequent incubation steps. Furthermore, analysis of only a few hundred cells per sample is possible. We examined the sensitivity of this method by comparing the percentages of positive cells in a spleen cell suspension after staining with a panel of monoclonal antibodies followed by analysis with the present immuno-beta-galactosidase method or standard flow cytometry. For almost all antibodies used, the percentages of positive spleen cells obtained with the immuno-beta-galactosidase method at least equalled those obtained with flow cytometry. Several fixatives, used to permanently adhere the cells to the slide's surface, were tested for the preservation of both morphological and antigenic structure. Glutaraldehyde and formol acetone proved to be the best choices in this respect. The present method combines high sensitivity with good morphology and is especially useful for immunophenotyping low cell numbers of heterogeneous populations.

Methodological aspects and application of the immunoperoxidase staining technique in diagnostic fine-needle aspiration cytology

The immunoperoxidase method was modified and adapted for use on cells obtained by fine-needle aspiration biopsy for routine diagnostic cytology. Combinations of different modes of fixation and graded trypsinization were tested. Best results were obtained with fixation in formol-acetone followed by enzyme digestion for 3-6 min; exact times were adjusted for the individual antigen. With optimal conditions as to fixation and proteolytic digestion, the method was found to be sensitive and reproducible and without artifactual background staining. Various intracytoplasmic antigens of diagnostic importance such as immunoglobulins, prostate-specific antigen, keratin, thyroglobulin, S-100, alpha-1-antitrypsin, and lysozyme in lymphoid cells, bone marrow cells, and tumor cells of epithelial and mesenchymal origin were detected. Staining of newly prepared or up to 2-yr-old specimens gave equally good results. Both cellular morphology and the results of immunoperoxidase staining can be studied simultaneously. The method is considered valuable for increasing accuracy of diagnostic cytology.

Immunocytochemical localization of lactoferrin in human neutrophils. An ultrastructural and morphometrical study

The subcellular localization of lactoferrin in human neutrophils was studied by an electron-microscopic immunoperoxidase method. This molecule was detected in small granules of blood polymorphonuclear leukocytes. A morphometrical analysis showed that there was no significant difference in the mean size between lactoferrin-positive and myeloperoxidase-negative granules. In contrast, the mean size of myeloperoxidase-positive granules was significantly larger than that of lactoferrin-positive granules. This indicates that lactoferrin is contained in the myeloperoxidase-negative, secondary, granules of human neutrophils. In immature bone marrow mononuclear neutrophils, lactoferrin was present in cytoplasmic granules of somewhat larger size than lactoferrin-positive granules of polymorphonuclear leucocytes. A morphometrical study showed that the mean size of lactoferrin-positive granules was significantly greater in immature bone marrow cells than in polymorphonuclear leucocytes. This indicates that lactoferrin-positive granules decrease in size as the cells mature. Besides cytoplasmic granules, lactoferrin was demonstrated in the Golgi complex and a part of the rough endoplasmic reticulum of immature bone marrow neutrophils, probably myelocytes and early metamyelocytes. These results show that lactoferrin is synthesized and packed into secondary granules in immature bone marrow neutrophils and therefore that the secondary granules are a type of secretory granule.

Estrogen binding sites and estrophilin histochemistry and their correlation with oestrogen receptor biochemistry

Since the application of mono- and poly-clonal antibodies to the estrogen receptor protein (estrophilin) classically admitted opinions about the interactions between estrogens and their target cells have changed. Biochemical assays of ER have been shown to provide false negative results; the key-mechanism seems to be located at the nuclear level, while until now most emphasis was put on cytosolic ER. In histochemistry, apparently contradictory reports have emphasized either cytoplasmic or nuclear labelling of estrogen binding sites (EBS). A lot of supputations have tried to explain in vitro translocations from the cytoplasm to the nucleus according to the physicochemical conditions which were used. Reading of some articles gives the impression that EBS histochemistry is yet an established and reliable method; commercially available histochemical "kits" may support this false idea. Therefore it is absolutely mandatory to intend to remain cautious and critical. Stepwise our knowledge is increasing; it is absolutely clear that the problems which did rise thanks to the "contradictory" histochemical studies gave a new impetus to both biochemical and histochemical research. Immunohisto- and cyto-chemistry of EBS and estrophilin go on in parallel and in correlation with biochemistry.

Neutralization test for BK virus: plaque reduction detected by immunoperoxidase staining

We developed an immunoperoxidase staining test to detect structural antigens of BK virus (BKV) in Vero cell cultures. This test was used to examine the neutralizing activity of human and immunized animal sera. It was shown that sera positive for BKV antibodies measured by hemagglutination inhibition test and enzyme-linked immunosorbent assay (ELISA) were able to prevent expression of BKV structural antigens in cell cultures. The correlation between titers in the hemagglutination inhibition test, levels of BKV IgG measured by ELISA, and the titers assayed by the immunoperoxidase neutralization test was high. We suggest that this type of test may be used instead of conventional neutralization tests for other viruses with slowly developing cytopathogenic effects.

Surface immunoglobulin light chain expression in pre-B cell leukemias

Cytofluorographic analysis of surface immunoglobulin (sIg) light chain clonal excess (CE), defined as (%kappa+ - %lambda+)/(%kappa+ + %lambda+) cells per discrete level of fluorescence intensity, was carried out on mononuclear cells of 32 leukemic patients. Eight demonstrated sIg light chain CE, including four blastic chronic myeloid leukemias (BL-CML), three "null" acute lymphoblastic leukemias (ALL), and one leukemic lymphoblastic lymphoma. Six of the leukemias demonstrated a kappa CE and two had a lambda CE. Sorted kappa+ PB cells from a BL-CML patient were shown to have a diploid DNA stem line and to bear the "common" ALL antigen. To provide further support for our finding of the expression of sIg light chains in ALL, we studied the REH cell line, derived from a "common" ALL patient and found cytoplasmic mu heavy chain and surface Ig lambda CE. Nucleic acid blotting experiments on REH revealed that both kappa genes had been deleted and that lambda genes had been rearranged, as expected in B cells expressing lambda light chains. Moreover, REH cells contained mu and lambda RNA. When REH cells were treated with TPA the amount of mu chain RNA increased by approximately fivefold and the amount of lambda chain RNA increased by approximately twofold. The finding of sIg light chain in pre-B cell leukemias and in the REH cell line, suggests that these leukemic cells are further differentiated along the B-cell lineage than was previously believed.

Immunocytochemistry: its evolution and criteria for its application in the study of epon-embedded cells and tissue

The word immunocytochemistry is currently used to describe a number of methods that can be employed to localize antigens within cells by means of antigen-specific antibodies. In this article we will review a number of these methods, including immunofluorescence, immunoperoxidase, avidin-biotin, and colloidal-gold techniques. The advantages and disadvantages of the various methods are discussed, special attention being focused upon immunocytochemical staining of plastic-embedded tissue. Studies on the light microscope level show that embedding tissue in plastic prior to immunoperoxidase staining not only improves visualization of antigen-specific staining but also provides an accurate and efficient means of prescreening tissue for antigen prior to immunocytochemical staining on the electron microscope level. Varying section thickness between 1 and 3 microns does not significantly influence staining, whereas the fixative used to preserve the tissue under study does. On the electron microscope level, the colloidal gold technique appears superior to immunoperoxidase staining. It is both esthetically more pleasing and highly sensitive. Of five different colloidal gold methods tested, the most sensitive is the two-step technique that employs an antigen-specific primary antibody followed by a gold-labeled secondary antibody. Throughout this article, special emphasis is placed on the use of proper controls, both on the light and electron microscope levels. Where possible, such controls should include substitution of specific antiserum with normal serum; the use of antigen-adsorbed antiserum; the use of antisera with specificities for antigens not present in the tissue being studied; the use of tissue previously shown to be stainable for the antigen; and if cultured cells are being studied, the use of a number of cell types that do not contain the antigen.

The distribution of lysozyme, alpha-1-antitrypsin, and alpha-1-antichymotrypsin in normal hematopoietic cells and in myeloid leukemias: an immunoperoxidase study on cytocentrifuge preparations, smears, and paraffin sections

Blood and bone marrow samples from 20 individuals with reactive conditions and 26 cases of acute and chronic myeloid leukemias were tested for the presence of lysozyme, alpha-1-antitrypsin (alpha-1-AT), and alpha-1-antichymotrypsin (alpha-1-ACT). We compared the reactivity of samples in smears, cytocentrifuge preparations, and paraffin sections. Lysozyme, alpha-1-antitrypsin, and alpha-1-antichymotrypsin were found only in polymorphonuclear leukocytes and monocytes and their precursors. Lymphocytes, E-rosetting cells, Con A-activated lymphocytes, natural killer (NK) cells, red blood cells, erythroblasts, and megakaryocytes were consistently negative. Leukemic myeloblasts showed definite reactivity for both alpha-1-antitrypsin and alpha-1-ACT, but not for lysozyme. By contrast, lysozyme was present in poorly differentiated leukemic monoblasts, while alpha-1-antitrypsin and alpha-1-antichymotrypsin showed only weak reactivity. More mature myeloid and moncytic cells showed positive staining for all three antigens tested with differences in staining distribution and intensity. In four cases of chronic myeloid leukemia (CML), circulating mature polymorphonuclear leukocytes were deficient in both lysozymne and alpha-1-antitrypsin. The use of lysozyme, alpha-1-antitrypsin, and alpha-1-antichymotrypsin identifies normal and leukemic cells of the myeloid-monocytic series at all stages of maturation and is applicable to a variety of sample preparations.

Immunological typing of acute lymphoblastic leukemia: concurrent analysis by flow cytofluorometry and immunocytology

For 60 cases of acute lymphoblastic leukemia (ALL) immunological typing was done concurrently by the avidin-biotin-peroxidase method using cytocentrifuged smears and by flow cytofluorometry for the study of surface antigens. The use of a large panel of antibodies detecting differentiation antigens allowed us to sub-classify 57/60 cases as 43 B-lineage ALLs and 14 T-lineage ALLs. The two types of ALL can be accurately distinguished by the expression of the antigens recognized by the antibodies of the clusters of differentiation CD19 (B4) and CD7 (Leu 9). Almost perfect agreement was obtained between the results of the two methods for antigens DR, CD10 (cALLA;J5) and CD7. A number of discordances were observed with other antigens [CD19 (B4), CD20 (B1), CD22 (To15), CD1 (T6), CD2 (T11), CD4 (T4), CD8 (T8), CD3 (T3), T9, T10]. In spite of these discordances, the avidin-biotin-peroxidase method can predict the lineage involved in most ALLs with a high degree of reliability. Nevertheless, for weakly expressed surface antigens (such as B4 and B1) the immunocytological method is less sensitive than flow cytofluorometry and can only approximately determine the stage of differentiation of neoplastic cells. Furthermore, the existence of cases which are at the same time negative with flow cytofluorometry and positive with immunocytology is consistent with the intracytoplasmic expression of certain differentiation antigens. Thus in the course of lymphoid differentiation, intra-cytoplasmic expression of T3, To15 and possibly J5 precedes their expression at the cell surface.

A monoclonal antibody-based immunoassay for human lactoferrin

Monoclonal antibodies against human lactoferrin define at least 3 and possibly as many as 6 different epitopes. A sandwich enzyme-linked immunoassay, using monoclonals against different epitopes, has been optimised for the measurement of serum lactoferrin. In 35 samples from healthy adults the mean lactoferrin content of serum from blood clotted overnight was 0.54 +/- 0.26 micrograms/ml.

Phenotypic characterization of 'non-T, non-B' acute lymphoblastic leukemia by a new panel (BL) of monoclonal antibodies

Peripheral blood and/or bone marrow leukemic cell suspensions from 49 patients with 'non-T, non-B' acute lymphoblastic leukemia (ALL) were analysed by flow cytometry using a new panel of four monoclonal antibodies. Anti-BL1 and anti-BL2 originating from NALM-6 and B35M lymphoblastoid cell lines, respectively. These antibodies recognize B-cell differentiation antigens: a heat stable non-immunoprecipitable antigenic determinant, and a 68 000 daltons glycoprotein molecule, respectively. BL5 and BL6 were derived by immunization with the promyelocytic cell line HL-60, recognizing antigens present on early hematopoietic cells: an 85 000 daltons MW glycoprotein (Pro-Im 1) and a heat stable antigen (Pro-Im2), respectively. All ALL patients studied had L1 or L2 morphology by the FAB classification and a blast count exceeding 50 per cent. There were 25 males and 24 females. Median age was 8 years (range 1-67 years). Thirty-nine cases were studied at initial presentation and 10 at relapse. Cells from 46/49 cases expressed BL2 and/or BL1, but were not reactive with BL5 or BL6. Three of 49 cases did not express BL1 or BL2. However, a small percentage of blasts from one case was positive for BL5 (13 per cent) and the other 2 cases were reactive with BL6 (20 per cent and 36 per cent, respectively). These were one adult and 2 pediatric patients that had other ALL markers and achieved a complete remission with appropriate ALL therapy. One of the BL6+ cases relapsed after 19 months with a change in phenotype to BL1+ BL2+ BL5- BL6-. This analysis shows that the majority of 'non-T, non-B' ALL's do express B-cell associated antigens (BL1/BL2) argumentative of their B-cell origin. A small subgroup does not express such antigens and may arise from a more immature cell, since they expressed antigens on early hematopoietic stem cells.

Surface immunoglobulin light-chain expression by the "common" all cell line REH

To provide further support of the B-cell lineage of "common" acute lymphoblastic leukemia (ALL), we studied the REH cell line and found not only cytoplasmic heavy chain but also surface lambda light-chain expression by flow cytometry. Nucleic acid blotting experiments on REH revealed that both kappa genes had been deleted and that lambda genes had been rearranged, as expected in B cells expressing lambda light chain. Moreover, REH cells contained mu and lambda RNA. When REH cells were treated with TPA the amount of mu chain RNA increased by approximately fivefold and the amount of lambda chain RNA increased by approximately twofold. The finding of surface immunoglobulin lambda light chain in the REH cell line, suggests that these leukemic cells are further differentiated along the B-cell lineage than was previously believed.

Immunocytochemical staining of cytocentrifuge prepared cultured cells: nonspecific staining and its elimination

In an attempt to localize hormones in cytocentrifuge-prepared cultured cells of small cell carcinoma of the lung (SCCL), various modifications of the immunoperoxidase (PAP) procedure (Sternberger, 1979) were tested. When using glutaraldehyde, formaldehyde, or p-benzoquinone fixation (Pearse & Polak, 1975) and rabbit antibodies in primary or bridging steps of the PAP procedure, nonspecific staining (false positives) could be elicited with the majority of rabbit antibodies tested, but not with antibodies from other animal sources. This problem could be eliminated by fixation of cells either with formalin-acetone (Mason et al., 1975) or, when using antibodies from a source other than rabbit, glutaraldehyde. It was not possible to localize ACTH in DMS-79, a human SCCL line known to produce this hormone. However, calcitonin was localized in the calcitonin-producing SCCL line DMS-53. Failure to localize ACTH in DMS-79 may be due to the lower levels of this hormone in DMS-79, as compared to the levels of calcitonin in DMS-53. This study emphasizes the importance of proper controls before concluding successful localization in a given immunocytochemical preparation of cultured cells.

Discordance between surface and cytoplasmic expression of the Leu-4 (T3) antigen in thymocytes and in blast cells from childhood T lymphoblastic malignancies

We have examined the expression of the Leu-4 (T3) antigen on the cell surface and in the cytoplasm of blast cells from 23 patients with T cell acute lymphoblastic leukemia and T cell lymphoblastic lymphoma. In the majority of cases (17), the Leu-4 antigen was absent from the cell surface; however, in 16 of these 17 cases, blast cells demonstrated cytoplasmic expression of Leu-4. This discordance between surface and cytoplasmic expression of Leu-4 was also found in thymocytes and appeared to be restricted to Leu-4, in that tests of other T cell antigens rarely revealed discordance between surface and cytoplasmic expression. To study further the cytoplasmic determinant identified by anti-Leu-4 in malignant T lymphoblasts, immunoprecipitation studies were performed that utilized biosynthetic labeling of established T cell lines derived from T lymphoblastic malignancies. By one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, identical Leu-4 polypeptide families were immunoprecipitated from surface Leu-4+ and surface Leu-4-/cytoplasmic Leu-4+ cell lines. Because T lymphoblastic malignancies represent proliferations of immature T cells, and because the cases studied demonstrated surface phenotypes corresponding to all of the proposed stages of T cell ontogeny, it appears that cytoplasmic expression of Leu-4 occurs early in T cell development. The reason for the failure of these immature T cells to transport the Leu-4 molecule to their surface remains to be elucidated.

A sensitive method for immunophenotyping stored leukemia and lymphoma cells with preservation of morphological detail

We describe a method by which density-separated mononuclear preparations of blood and bone marrow may be stored and batch-processed for immunophenotyping by the indirect immunoperoxidase (IP) technique. The method gives excellent preservation of cellular detail thus permitting clear morphological categorization of IP-positive and IP-negative cells. We compared the immunofluorescence (IF) and IP techniques for estimation of the proportions of cells displaying a variety of antigens; with normal blood cells the results were closely similar but with chronic lymphocytic leukemia (CLL) cells, IP was superior to conventional IF. Using 910 D7, a new anti-la antibody, we were able to observe directly the presence of la-positive lymphocytes and monocytes in normal peripheral blood and la-positive granulocyte precursor cells from 2 cases of chronic granulocytic leukemia (CGL) in transformation. The method is useful for immunophenotyping of cases of lymphoproliferative disorder (LPD) and for morphological identification of specific antigen-positive cells.

Phenotypic analysis of an established cell line derived from a patient with Hodgkin's disease (HD)

This report describes the phenotypic analysis of a cell line obtained from a female patient with the nodular sclerosing subtype of Hodgkin's disease (HD). The cell line has a neoplastic karyotype and is stable in culture in the absence of feeder layers or growth factors. Phenotypic analysis of this cell line shows that it cannot easily be characterized as either a lymphocyte, macrophage or granulocyte but resembles in its characteristics certain HD lines already described in the literature. The cell line carries the antigen defined by the Ki-1 monoclonal antibody, shows myeloid markers on a proportion of cells and has cytoplasmic UCH-T1.

[Immunohistochemical drug detection in autopsy material]

Drugs (barbiturates) could be qualitatively identified in formalin-fixed and in paraffin-embedded autopsy material, as well as in fresh-frozen unfixed tissue by using the PAP method. Sensitivity could be considerably increased by application of an additional antibody. The practical use of this kind of determination is the possibility of retrospective examination if more suitable material is not available.

Method for the simultaneous labelling of terminal deoxynucleotidyl transferase (TdT) and membrane antigens

A method for the simultaneous labelling of terminal deoxynucleotidyl transferase (TdT) and membrane antigens is described. TdT is visualised in the cell nucleus with the peroxidase-antiperoxidase (PAP) method, and the immunogold method is used in combination with monoclonal antibodies against membrane antigens. The morphology of the labelled cells is well preserved for analysis by light microscopy and the preparations obtained can be kept permanently. This method is useful for the analysis of mixed cell proliferations, particularly in leukaemias.

Identification of cellular immunoglobulins in chronic lymphocytic leukaemia by immunoperoxidase staining

An indirect immunoperoxidase technique has been used for visualisation of cellular immunoglobulins in chronic lymphocytic leukaemia. Baker's formol calcium was used as fixative. Monoclonal light and heavy chain patterns were demonstrated in 24 out of 27 cases. Only one case did not have any demonstrable immunoglobulins. The presence of alpha or gamma heavy chain immunoglobulin isotypes in leukaemic lymphocytes was found to be related to low mouse rosetting capacity (p less than 0.05).

Lactoferrin-deficient neutrophil polymorphonuclear leucocytes in leukaemias: a semiquantitative and ultrastructural cytochemical study

Semiquantitative analysis of lactoferrin deficiency in neutrophil polymorphonuclear leucocytes in various haematological and non-haematological disease was carried out by scoring polymorphonuclear leucocytes stained for lactoferrin by the immunoperoxidase method. The staining patterns for lactoferrin were classified into four types (0-III) based on the intensity of reaction, and the sum of the ratings of 100 polymorphonuclear leucocytes was considered as "lactoferrin score" with a possible range of 0-300. As a result, significantly low lactoferrin-scores were frequently observed in acute leukaemias and the acute phase of chronic leukaemias. Of 35 cases with leukaemias, lactoferrin-negative polymorphonuclear leucocytes (type 0) were observed in the following cases: eight cases of acute myelogenous leukaemia (8/14), a case of chronic myelogenous leukaemia (1/10) in blast crisis, one of acute promyelocytic leukaemia (1/1), one of acute monocytic leukaemia (1/2), and a case of chronic myelomonocytic leukaemia (1/2) in a transitional phase to an acute myelomonocytic leukaemia. In two cases of acute myelogenous leukaemia, in which the majority of polymorphonuclear leucocytes were negative for lactoferrin, ultrastructural cytochemical study revealed total lack of specific granules in these polymorphonuclear leucocytes. This suggests that lactoferrin is localised in the specific granules of neutrophils as has been postulated previously by others.