Detection of melanoma cells in bone marrow using monoclonal antibodies. A comparison of fluorescence activated cell sorting (FACS) and conventional immunofluorescence (IF)

Immunohistochemical Reactivity of the Antimelanoma Monoclonal Antibody Mel-1

The immunohistochemical reactivity of the monoclonal antimelanoma antibody MEL-1 was evaluated on frozen sections of 9 malignant melanomas, 5 nevi, 1 squamous cell carcinoma, 1 basal cell carcinoma, 2 benign dermal fibrous histiocytomas, 1 infiltrating ductal and 2 infiltrating lobular carcinomas of the breast, 1 primary squamous cell carcinoma and 1 adenocarcinoma of the lung, 1 lung metastasis of gastric adenocarcinoma, 1 adenocarcinoma of the large bowel, 1 lymph node, 1 case of malignant histiocytosis and one of lymph nodal immunoblastic lymphoma, and 1 biopsy of oral cavity mucosa. In primary and metastatic malignant melanoma, junctional nevi, and the upper half of compound and dermal nevi, the staining was intense. Also, benign dermal fibrous histiocytoma and the case of lymph nodal malignant histiocytosis showed an intense reactivity, whereas the immunostaining positivity of the squamous cell carcinoma of the skin, the lung adenocarcinoma, the squamous cutaneous and mucosal epithelium, and the sweat and sebaceous glands was slight. In ductal and lobular infiltrating carcinoma of the breast only focal areas or isolated tumor cells were positive. The lack of reactivity of deep dermal melanocytes of compound and dermal nevi may be correlated with a different antigenic phenotype of the melanocytes. After discussion of the technical problems, the application of MEL-1 was suggested, for diagnostic purpose, to identify lymph nodal metastases in cases of primary self regressed malignant melanoma and to detect lymph nodal metastatic microfoci of malignant melanoma.

Limitations of the immunocytochemical detection of isolated tumor cells in frozen samples of bone marrow obtained from melanoma patients

We report on a case of a 70-year-old woman with an ocular melanoma, which was diagnosed and treated 14 years ago. The patient was referred to the hospital with a suspected lymphoma. Cytological examination of bone marrow proved a marked infiltration with melanoma cells. Because detection of isolated tumor cells in the bone marrow of patients with various types of tumors was shown to be of prognostic significance and since current tumor-staging techniques are unable to detect single disseminated tumor cells or small aggregates of tumor cells, which might be the seed for subsequent metastatic relapse, we therefore evaluated the feasibility of immunocytochemical screening of bone marrow aspirates of 36 melanoma patients in different clinical stages using three monoclonal antibodies against melanoma-associated antigens in comparison with 43 non-melanoma control patients. Two of these antibodies (HMB45 and NKI-beteb) are directed against the melanoma antigen gp100/pmel17, whereas the third one (TA99) recognizes gp75/Tyrosinase-related protein 1 (TRP-1). None of the patients demonstrated a macroscopic bone marrow infiltration as was present in our patient with metastatic ocular melanoma. Seven (20.6%) of the 34 eligible melanoma patients presented with cells in the bone marrow positive for one or more of the above-mentioned melanosomal markers. Four of the positive patients were clinically free of tumors by the time of puncture, whereas the remaining 3 patients showed overt metastases in the subcutaneous fat (2 patients) and the brain (1 patient). On the other hand, 20 (66%) of the 29 patients with negative bone marrow findings also presented with clinical advanced disease with overt metastasis in the skin, lymph node, spleen, liver, lung, bone and brain. In conclusion, immunocytochemical screening of bone marrow samples is a feasible procedure that allows the detection of micrometastatic tumor cells in a subset of melanoma patients. Massive invasion of bone marrow with melanoma cells is a rare event even in far-advanced metastatic stages and no clear correlation between tumor load and bone marrow infiltration could be established.

In vitro detection of occult bone marrow metastases in patients with colorectal cancer hepatic metastases

PURPOSE

The purpose of this study was to assess the immunocytochemical status of bone marrow aspirates from patients with clinically isolated hepatic metastases to test the hypothesis that such findings would allow improved patient selection for liver-directed treatment.

METHODS

All patients had biopsy-proven or presumed colorectal cancer metastatic to the liver and were scheduled for an operative procedure for hepatic resection or for hepatic artery catheter and chemotherapy pump implant. Immunocytochemical analysis of bone marrow aspirate smears was performed with a panel of monoclonal antibodies directed toward cytokeratins, Lewis Y antigen and A-33 colorectal epitopes.

RESULTS

Data from 80 patients indicated that bone marrow reactivity was present in 9.5 percent of those with resectable hepatic metastases and in 34 percent of those not resected (P = 0.03). No single monoclonal antibody or combination produced better discrimination.

CONCLUSIONS

Presence or absence of presumed occult colorectal cancer cells in the bone marrow of patients with isolated hepatic metastases is biologically interesting, but not useful in selecting or altering patient management.

Functional immunocytopathology and the diagnosis of bone marrow micrometastases

Immunocytochemical methods offer a new dimension for cytopathology in the diagnosis, prognosis and biology of neoplastic diseases. This concept is illustrated with particular respect to the immunodetection of bone marrow micrometastases and the role of cytologically demonstrable functional parameters in prognosis and therapy planning. A future role for the polymerase chain reaction (PCR) in this diagnostic sphere is proposed.

A digital image microscopy system for rare-event detection using fluorescent probes

Instrumentation for rare-event analysis should be capable of reliably detecting infrequent cells (less than 1:10,000) while both excluding false-positive signals and including true positive cells found in multicell clumps. We have developed a digital image microscopy (DIM) system in which a cytospin of 2 million cells is scanned with an intensified video camera (ISIT) using an IBM PC AT microcomputer-controlled microscope stage. PASCAL software controls the stage and analyzes video input, storing the location of positive cells to magnetic disk. The user can then "replay" each positive cell under computer control for either visual confirmation or analysis using other fluorescent probes. The computer requires 24 min to scan a cytoprep of 2 million cells, while playback for visual confirmation by the user averages 5 min. Using Hoechst-33342 premarked cells seeded into bone marrow as a model system, we found that the DIM system reliably detects one target cell per million marrow cells. With appropriate immunological markers, this system will aid in evaluating bone marrow purged of tumor cells prior to transplantation and should also be useful for detection of minimal residual disease in blood or bone marrow from patients with leukemia or solid tumors.

Monoclonal antibody detection of carcinoma cells in bone marrow biopsy specimens from breast cancer patients

The possibility of using immunologic methods for detecting metastatic cells in bone marrow samples from breast cancer patients was investigated. The MBr1 monoclonal antibody, which recognizes a membrane antigen on breast carcinoma cells and is unreactive on normal bone marrow cells, seemed to be an adequate reagent for this kind of approach. When human leukocyte suspensions artificially contaminated with mammary tumor cells were tested by MBr1 immunofluorescence, it was demonstrated that the added tumor cells could be specifically discriminated from normal cells and that as little as one tumor cell in 200,000 could be detected. With the same methodology we screened bone marrow biopsies from breast cancer patients with apparently uninvolved lymph nodes at the moment of surgery. Immunoreactive tumor cells were detected by the MBr1 antibody in 17% of N- patients. None of the bone marrow samples showed any evidence of tumor involvement by conventional histologic analysis.

Radioimmunodetection of cancer with monoclonal antibodies: current status, problems, and future directions

Early studies of immunoscintography with affinity-purified 131I-labeled polyclonal antibodies reactive against oncofetal antigens such as carcinoembryonic antigen (CEA) were moderately successful in detecting metastatic colorectal carcinoma. However, because of low tumor to background ratios of isotope, background subtraction techniques using 99Tc-labeled albumin were required to visualize small lesions. Antisera were often of low titer and lacked specificity. These problems could be overcome for the most part following the development of highly specific monoclonal antibodies (MoAb) against a variety of tumor-associated antigens. A number of clinical trials using 131I- or 111In-labeled MoAb to image tumors have demonstrated successful localization without the use of subtraction techniques. Variables limiting the usefulness of murine MoAb for diagnosis have included increased localization in liver and spleen, tumor vascularity and heterogeneity of antigen expression, and development of human antimurine globulins. Methods to overcome some of these problems are discussed. Radiolabeled MoAb appear useful as an adjunct to conventional diagnostic techniques both as a means to predict which antibodies might be useful for treatment and, in select patients, as a basis for treatment decisions.

A monoclonal antibody micromethod for studying fetal lymphocytes: potential for prenatal diagnosis of inherited immunodeficiencies

Using monoclonal antibodies and indirect immunofluorescence an easy, reliable, inexpensive micromethod for the quantitative analysis of fetal lymphocyte markers was developed. Monoclonal antibodies specific for identification of all peripheral T lymphocytes (OKT 3), the subclass of suppressor/cytotoxic T lymphocytes (OKT 8), and for B lymphocytes (OKla 1) were employed. This technique will permit in utero recognition of immunodeficiency states which alter the ratio of these cell types.

Improved detection of rare CALLA-positive cells in peripheral blood using multiparameter flow cytometry

A major limitation to the detection of rare cell types in the peripheral blood using monoclonal antibodies is nonspecific binding of the antibody reagent to normal cells. Detection of rare common acute lymphoblastic leukemia antigen (CALLA)-positive cells in peripheral blood is significantly improved by using multiple flow cytometric parameters to exclude a variety of mature blood cells which may nonspecifically bind the antibody reagent. Monocytes and granulocytes are excluded by gating out cells with high 90 degrees light scatter. By gating on red fluorescence, a variety of mature cell types binding to phycoerythrin (PE)-conjugated Leu 3, Leu 2, and M3 monoclonal antibodies are also excluded. CALLA-positive lymphoblasts from 6 consecutive patients were not excluded on the basis of these parameters. Gating on log 90 degrees light scatter and log red fluorescence in this fashion reduced the incidence of nonspecific binding to peripheral blood mononuclear cells of a fluorescein-conjugated irrelevant monoclonal antibody by 98% from 308 cells per million to 5 cells per million. One CALLA-positive lymphoblast per 100,000 peripheral blood mononuclear cells could be detected in mixture experiments using this method. The normal range of CALLA-positive cells in adults is less than 16 cells per million peripheral blood mononuclear cells. This low background of CALLA-positive peripheral blood cells may permit the detection of early leukemic relapse in acute lymphoblastic leukemia by analysis of the peripheral blood. This methodology can be applied to the detection of any rare cell type by using phycoerythrin-conjugated antibodies to markers that the cell type does not possess.