Interferon enhances the natural killer cell activity of the retinoblastoma patients to autologous retinoblastoma cells

The cytotoxic activities of the peripheral lymphocytes prepared from two retinoblastoma patients to freshly isolated autologous tumor cells were measured using 51Cr-release assay. The retinoblastoma cells of the two patients resisted lysis by unstimulated effectors, whereas interferon(IFN)-stimulated effector cells gave a significantly higher cytotoxicity. This result implies that IFN therapy may be potent in treating high-risk retinoblastoma patients.

S-antigen immunoreactivity in trilateral retinoblastoma

Using monoclonal antibody MAbA9-C6, which identifies an antigenic determinant of S-antigen retained in fixed tissue sections, we investigated S-antigen immunoreactivity in the ocular and brain tumors of four cases of trilateral retinoblastoma. In the eye, S-antigen immunoreactivity was present in all retinoblastomas examined, as well as one retinocytoma characterized by benign appearing cells including fleurettes. S-antigen immunoreactivity was focally present in two of the four brain tumors examined. Additionally, two intraocular medulloepitheliomas, one of which contained well-defined rosettes, and 16 primary intracranial tumors, including seven pineal gland tumors and nine other lesions, some of which histopathologically may resemble retinoblastoma, were examined. S-antigen immunoreactivity was observed in two pineal gland tumors but not the remaining nine primary intracranial neoplasms or the two intraocular medulloepitheliomas. Our results further substantiate the immunologic relationship between the retina and the pineal gland, and tumors originating in these tissues.

Expression of the HNK-1 carbohydrate epitope in human retina and retinoblastoma. An immunohistochemical study with the anti-Leu-7 monoclonal antibody

Fifty formalin-fixed and paraffin-embedded retinoblastoma specimens and five normal human eyes were studied with the monoclonal anti-Leu-7 antibody, directed against the HNK-1 carbohydrate epitope that is shared by human natural killer cells and many neuronal, glial and neuroectodermal cells. The laboratory method was a sensitive immunohistochemical staining procedure, and neuroectodermal tumours that usually express this epitope were used as positive controls. In the human retina, Müller cell membranes were positively stained, but additional staining of neuronal cells was not excluded at the light microscopical level. A positive cytoplasmic reaction was also seen in ciliary and retinal pigment epithelial cells. All but one intraocular retinoblastomata studied contained cells staining positively for the HNK-1 epitope, but these cells were probably not neoplastic. Although positive reaction has previously been reported in three retinoblastomata, the present results suggest that positive cells are derived from entrapped and infiltrated retina. Staining of adjacent sections against leukocyte common antigen suggested that the positively staining cells were not natural killer cells.

In vitro and in vivo growth of an intraocular retinoblastoma-like tumour in F-344 rats

Retinoblastoma-like cells grew in colonies on the bottom of tissue culture flasks. The population doubling time was 19 h. Tumour cells from cell cultures had a 39% plating efficiency, and fresh tumour cells from intraocular tumours had a 32% plating efficiency in colony forming assays. Inoculation of 1.5 X 10(4) tumour cells in the vitreous of F-344 rats resulted in a 100% tumour take and regularly growing tumours with a doubling time of 3 days. The tumour take-rate was not changed in wholebody immunosuppressed animals. The tumour volume was assessed under a stereo microscope, and it was possible to divide the tumours into 4 groups according to the number of intraocular tumour cells. Tumour growth caused eye perforation in 89% of the inoculated eyes. Spontaneous tumour regression was not seen in non-perforation groups. Immunosuppression with whole-body irradiation and dense traumatic cataract had no significant effect on the growth. It is concluded that this animal retinoblastoma-like tumour is suitable for quantitative therapy studies in vivo and in vitro.

Immunogenetic studies in retinoblastoma

In three unrelated families with transmitted retinoblastoma 43 members were tested for HLA-A, B, C, and DR antigens. On 18 patients, 16 unaffected relatives, and 16 controls, mixed lymphocyte cultures were carried out and the response to mitogens, phytohaemagglutinin, concanavalin A, and pokeweed mitogen examined. There were no associations of retinoblastoma with any HLA antigen. A reduction in T cell function is suggested by the results of the mitogen tests.

Expression of the photoreceptor-specific S-antigen in human retinoblastoma

This work presents an immunofluorescent study of the distribution of the photoreceptor-specific S-antigen in human retinoblastoma, using mouse monoclonal antibodies. Three cases of differentiated retinoblastoma displayed S-antigen immunoreactivity with various patterns of labeling which depended on the degree of differentiation of the area studied. Flexner-Wintersteiner rosettes and fleurettes were labeled only with monoclonal antibody S2D2, whereas undifferentiated areas were labeled with four different anti-S-antigen monoclonal antibodies, including S2D2. On the other hand, the three undifferentiated retinoblastomas did not show any labeling with these antibodies. The presence of S-antigen in differentiated retinoblastoma confirms that the origin of this tumor is from the photoreceptors, but the question remains unanswered for undifferentiated retinoblastoma for which another origin--glial or primitive neuroectodermal cells--may be proposed.

A human retinoblastoma cell line expressing the common acute lymphoblastic leukemia antigen and displaying an unusual chromosome abnormality

A new continuous cell line derived from an untreated human retinoblastoma has been established. This cell line, FMC-RB1 is strongly positive for common acute lymphoblastic leukemia antigen and shows a number of ring chromosomes and two marker chromosomes considered to be derivations of chromosome #17; the nonrandom chromosomal changes associated with retinoblastoma, particularly the loss of a chromosome #13 or the deletion of 13q14 was not observed. The establishment of the cell line initially required the presence of bone marrow stromal cells. Morphologically, this cell line grew as a suspension of small round cells in grape-like clusters with periodic "shedding" of single cells. FMC-RB1 could be cloned in soft agar, even in the absence of bone marrow stromal cells as "feeders", making it suitable for a variety of biological studies.

Studies of ocular retinoblastomas with immunoperoxidase techniques

15 cases of ocular retinoblastomas, 10 differentiated and 5 undifferentiated, were studied with the following antibodies: neuron-specific enolase, S100, and tubulin. All cases turned out negative with S100 and tubulin labeling. The well-differentiated retinoblastomas were NSE-positive, and only 2 of the 5 undifferentiated retinoblastomas were positive for the same antibody. The observed results let us conclude that S100 and tubulin are not useful in diagnosing this entity and that enolase, although it showed its value in the differentiated retinoblastomas, did not have the same effect in the undifferentiated retinoblastomas, as it was negative in 3 out of 5 cases.

Antigenic modulation in retinoblastoma: a flow cytometric study

Flow cytometry (FCM) was used to investigate antigenic expression and modulation during the cell cycle of Y-79 and WERI-Rb1 tissue cultured retinoblastoma cell lines using a polyclonal anti-Y-79 antibody and fluorescein conjugated lectins. Several Y-79 resting cell populations were identified by FCM analysis of antibody binding, while only a single population with uniform antigen expression was found to exist in the synthetic and mitotic phases. WERI-Rb1 cells bound antibody approximately equally in each phase of the cell cycle. Multiple cell populations with different lectin binding affinities were seen in the resting phase with FITC-concanavalin A, FITC-ricinus communis-60 and FITC-ricinus communis-120 (FITC-RCA-120). During the S-phase of the cell cycle, a higher percentage of cells bound FITC-RCA-120 and FITC wheat germ agglutinin. The relationship between antigenic expression during the cell cycle and treatment considerations in retinoblastoma is discussed.

Retinal S antigen and retinoblastoma. A monoclonal antibody histopathologic study

Using monoclonal antibody MAbA9-C6, which defines an epitope of retinal S antigen retained in fixed-tissue sections, we investigated S-antigen immunoreactivity in human fetal eyes from different gestational periods and 19 cases of retinoblastoma. S-antigen immunoreactivity was first observed in the outermost portion of the neuroblastic cell layer in the retina of a human fetus at 18 weeks' gestation, a stage preceding photoreceptor differentiation, and at all later stages examined thereafter. All adult eyes containing normal photoreceptors bound MAbA9-C6. In retinoblastomas, several different patterns of S-antigen immunoreactivity were recognized. In seven cases, S-antigen immunoreactivity appeared to be associated with normal photoreceptor elements incorporated into the growing tumor. S-antigen immunoreactivity was associated with fleurettes within the retinoblastoma in three cases and Flexner-Wintersteiner rosettes in seven cases. In 11 cases, S-antigen immunoreactivity was associated with isolated tumor cells. Our results show that S antigen may be a useful marker in the study of the embryologic development of the human retina and antigenic expression and modulation in retinoblastomas.

Retinal S-antigen and retinoblastoma: a monoclonal antibody and flow cytometric study

Retinal S-antigen was demonstrated in the WERI-Rb1 and to a lesser extent the Y-79 tissue cultured retinoblastoma cell lines as well as an ethanol-fixed, paraffin-embedded retinoblastoma by an indirect immunoperoxidase technique using monoclonal antibody MAbA9-C6, and by flow cytometric analysis (FCM) using MAbA9-C6 and MAbA1-G5. In fixed tissue sections, S-antigen immunoreactivity was restricted and localized to small numbers of retinoblastoma cells, including Flexner-Wintersteiner rosettes. By FCM, MAbA9-C6 bound to 15.4% of WERI-Rb1 cells and to 10.99.7% of Y-79 cells whereas MAbA1-G5 bound to 14.66% of WERI-Rb1 and to 4.23% of Y-79 cells respectively. Cell cycle analysis showed that S-antigen was predominately expressed in the resting (G0/G1) phase. The usefulness of MAbA9-C6 in studying the embryological development of the retina and as a marker protein for studying antigenic expression and modulation in retinoblastomas is discussed.

Immunohistochemical evidence for preproenkephalin A synthesis in human retinoblastoma

Human retinoblastoma contains clusters of cells immunoreactive for methionine-enkephalin and methionine-enkephalin-arginine-phenylalanine. Some tumour cells also exhibited methionine-enkephalin-arginine-glycine-leucine-like immunoreactivity. The results are in agreement with those obtained with similar testing of neuroblastoma cell cultures. It is concluded that some human retinoblastoma cells are capable of synthesizing preproenkephalin A or parts of this molecule.

Toxicity of a monoclonal F(ab')2:ricin A conjugate for retinoblastoma in vitro

The toxic A chain of the poison ricin has been conjugated to the F(ab')2 fragment of a retinoblastoma-specific murine monoclonal antibody. The conjugate was toxic in vitro to Y-79 retinoblastoma cells at a concentration of approximately 5 X 10(-10) M; Y-79 retinoblastoma cells were the immunizing cells in the production of the monoclonal antibody. Against a second retinoblastoma cell line, the conjugate was toxic at a concentration of approximately 10(-9) M. Ricin A chain alone was not toxic to either of these cell lines at concentrations less than 4 X 10(-8) M. The conjugate was no more toxic than was ricin A chain against five control cell lines in vitro. The effect of the conjugate on retinoblastoma-derived cells was concentration dependent. Concentrations less than a "minimum" concentration were not cytotoxic, despite an excess of conjugate molecules over target cells. Concentrations greater than the minimum toxic concentration rapidly reached maximal toxicity, suggesting that antigenic sites were saturated. No clinical, hematologic, or renal toxicity was noted when mice were given injections of the conjugate at 1 mg/kg, or free ricin A chain at 0.375 mg/kg.

Significance of carcinoembryonic antigen in retinoblastoma

The role of estimating the serum carcinoembryonic antigen (CEA) in the diagnosis and prognosis of retinoblastoma cases has been evaluated. Although the mean serum CEA titre in children with retinoblastoma was higher than that in control children (p = 0.01), the serum CEA level itself was found not to be a useful marker in the diagnosis of retinoblastoma. A significant correlation of serum CEA titre with progression or regression of the disease observed during therapy in most cases indicated that serial assays of serum CEA may be important in the follow-up of cases with retinoblastoma. The lower CEA values in aqueous humour and subretinal fluid from eyes with retinoblastoma than in the serum suggests that the tumour does not secrete the CEA.

Cytotoxic activity of lymphocytes from F 344 rats bearing intraocular tumor derived from human adenovirus 12-induced retinoblastoma-like cell line

Lymphocyte cytotoxicity using 51Cr releasing assay was investigated in 10 F344 rats bearing intraocular tumor derived from human adenovirus 12 (Ad 12)-induced retinoblastoma -like cell line (EXP-5). Lymphocytes obtained from tumor bored animal (1 X 10(6)/well) incubated with 51Cr-labelled EXP-5 cells (1 X 10(5)/well) for 24 hours, and counted by beta-scintillation counter. The cytotoxic activity of lymphocytes of transplanted animals was higher in 3 out of 10 subjected rats (24-30%) than in 10 rats of control (3-5%). The results support the view that the correspond animal model in its resemblance and suggested that the rats with retinal tumor have concomitant cell-mediated immunity in the early stage of tumor bearing.

Retinoblastoma: tissue culture lines and monoclonal antibody studies

Retinoblastoma patients have cellular and humoral reactivity towards antigens expressed on retinoblastoma cells. We report the ultrastructural, cytogenetic, and immunologic features of four new retinoblastoma derived tissue culture cell lines. Studies with hybridoma produced monoclonal antibodies demonstrate that these lines share antigens with a previously described long-term allogeneic retinoblastoma derived tissue culture cell line, as well as with antigens on fresh retinoblastoma.

Immunocytochemistry of neuronal and glial markers in retinoblastoma

An immunocytochemical study of 30 retinoblastomas was carried out using antibodies to neuronal and glial markers. The tumours were found to react with antibodies to neuron-specific enolase (NSE), a marker for neuronal elements, and S-100 and glial fibrillary acidic protein (GFAP), both of which are proteins present in glia. Two distinct cell populations were found within the tumour: the first, composed of anaplastic tumour cells at various stages of differentiation, showed both NSE and S-100 immunoreactivity; the second cell type, which immuno-stained for S-100 and GFAP, resembled mature glial cells. The results of this study indicate that the retinoblastoma may arise from a pluripotential primitive cell partially retaining neuronal and glial characteristics.

Cell-mediated immunity in F 344 rats bearing intraocular tumors derived from human adenovirus 12-induced retinal tumor

The eyes of 10 F344 rats were inoculated with retinal tumor cells (EXP-5 cell line) induced by human adenovirus 12. The animals were killed at 4 weeks thereafter, and the cytotoxicity of their lymphocytes was investigated by using 51Cr-releasing assay. The percentage of EXP-5 cells killed in vitro by lymphocytes was higher in 10 rats with ocular tumors (24.6% +/- 6.1%, mean +/- SD) than in 10 control rats (6.2% +/- 1.8%). Morphologic investigation using syngeneic spleen cells confirmed the presence of lymphoid cells, resembling T-lymphocytes, adhering to EXP-5 cells. The influence of subcutaneous injection of EXP-5 cells on the growth of intravitreously injected tumor cells was investigated. Cells injected subcutaneously prior to intravitreous injection elicited an immune response that was capable of controlling vitreous tumor growth. These findings suggest that the rats with transplanted retinal tumors develop a cell-mediated immune response in the early stage of tumor bearing, and that a state of pre-existing specific immunity can overcome so-called "immunologic privilege" of the vitreous body.

Hanganutziu-Deicher heterophile antigen in human retinoblastoma cells

We investigated the possible existence of Hanganutziu-Deicher antigen (HD antigen) on retinoblastoma cells by means of indirect membrane immunofluorescence and a complement-dependent antibody-mediated cytotoxicity test. We prepared antiserum in the chicken by immunization with purified equine hematoside highly specific to HD antigen. Three kinds of retinoblastoma cell lines, Y-79, WERI-Rb 1, and TOTL-1, showed positive membrane staining. Y-79 and TOTL-1 cells were also confirmed by the cytotoxicity test to possess HD antigen. Retinoblastoma cells freshly isolated from two patients had a positive membrane immunofluorescence. These results indicated that HD antigen was expressed in human retinoblastoma cells in vitro as well as in vivo.

Carcinoembryonic antigen in retinoblastoma. An immunohistochemical study

Pathological amounts of carcinoembryonic antigen (CEA) have earlier been reported in the plasma of patients with retinoblastoma, and it has been suggested that CEA determinations be used in the follow-up of treatment of these patients. In the present study, 47 retinoblastoma specimens from the years 1962-1982 were examined. These specimens represented different clinical and pathological tumour types. Colon adenocarcinomata positive for CEA were used as controls. The laboratory method was a highly sensitive immunohistochemical peroxidase-staining procedure. By this method, CEA was not found in any of the retinoblastomata examined. It is probable that retinoblastoma does not produce CEA, but in theory it may indirectly increase the CEA titre or, on the other hand, be fully independent of CEA. Only after this relationship has been thoroughly clarified can determinations of plasma CEA in patients with retinoblastoma be used in clinical work.

Ocular tumors react with anti-neuroblastoma monoclonal antibodies

The reactivities of mouse monoclonal antibodies directed against human neuroblastoma and peripheral melanoma associated antigens, with human retinoblastoma and choroidal melanoma cell lines were tested. Segregation of antigenic determinants according to each tumor class and cell line were observed. Three retinoblastoma cell lines and one fresh tumor explant showed determinants detected by two human neuroblastoma antisera, while the choroidal melanoma showed one determinant present on a peripheral melanoma but not neuroblastomas nor retinoblastomas, suggesting certain potential distinctive tumor related determinants.

Monoclonal antibody UJ 127:11 detects a 220,000-240,000 kdal. glycoprotein present on a sub-set of neuroectodermally derived cells

The monoclonal antibody UJ 127-11 was raised following immunization of mice with human foetal brain and subsequent somatic cell hybridization of spleen cells with the mouse myeloma cell line P3-X63-Ag8-653. Studies on normal foetal and adult tissues show that, by indirect immunofluorescence, the antigen recognized by UJ 127:11 is restricted in its expression to cells of neural rather than glial origin. Neural tumours such as neuroblastoma, medulloblastoma and ganglioglioma (neural component) bind the monoclonal antibody whereas malignancies originating from glial cells do not bind UJ 127:11. Biochemically the monoclonal antibody has been shown to bind to a glycoprotein of 220,000-240,000 mol. wt. under reducing and non-reducing conditions. Despite similarities in the molecular weight between human fibronectin and the antigen recognized by UJ 127:11, they have different serological and biochemical characteristics, suggesting that the monoclonal antibody is not binding to either cell or plasma fibronectin.

A study of astrocytes in retinoblastomas using the immunoperoxidase technique and antibodies to glial fibrillary acidic protein

We identified astrocytes in 12 of 14 randomly selected formalin-fixed Paraplast-embedded retinoblastomas, using the avidin-biotin-peroxidase complex of the immunoperoxidase techniques and antibodies to purified glial fibrillary acidic protein. In two of these eyes, both of which had extensive choroidal invasion by retinoblastoma, we found no tumor cells containing glial fibrillary acidic protein. Astrocytes were observed in metastases within the neurologic tissue of the central nervous system in two cases, but were rarely noted in metastatic foci within the subarachnoid space, and were not found in distant metastases to other sites. These findings suggested that although some astrocytes may become incorporated into retinoblastomas from the retina as the neoplastic cells proliferate and the tumor grows, others proliferate in response to the tumor. Although we found foci of cells containing glial fibrillary acidic protein in some retinoblastomas, convincing evidence of glial differentiation from tumor cells was not observed in any of the retinoblastomas we studied.

Substance P immunoreactivity in normal human retina and in retinoblastoma

Substance P (SP) immunoreactivity was demonstrated using the indirect immunofluorescence technique in one normal and one retinoblastomatous human retina. In the normal retina SP immunoreaction was located in nerve fibres but not in the neurons in the inner plexiform layer. A similar location was observed in the histologically normal areas of the retinoblastoma sample. SP immunoreactive neurons, probably amacrine cells, were, however, observed in the transitional area between the normal retina and the tumour. The tumour mass, although mainly SP negative, contained clusters of pleomorphic cells with an intense SP immunoreaction. The general distribution of SP immunoreaction in human retina resembles that of other mammals. The positive SP immunoreaction in retinoblastoma cells suggests that the tumour either may have its origin in the amacrine cells or that the retinoblasts are capable of redifferentiating in the direction of the amacrine cell population. The general problems concerning the origin and pathogenesis of retinoblastoma are discussed.