Inhibition of transplanted sarcomas mediated by BCG in rats with a defined immunological deficit

Experiments were undertaken to test the hypothesis that a major component of BCG contact-induced inhibition of syngeneic tumour growth in rats is not dependent on the participation of thymus-processed (T) cells. Hosts were deprived of T cells by thymectomy followed by either lethal irradiation (850 rad) and bone marrow reconstitution, or repeated whole body irradiation to a total dose of 1,000 rad. After 6 weeks had elapsed to allow for bone marrow restitution, rats were challenged with trypsinized sarcoma cells admixed with Glaxo strain BCG. For sarcoma P7, host T-cell deprivation did not significantly diminish the capacity of BCG to prevent the progressive development of this neoplasm from an inoculum of one million cells. Under similar conditions, the incidence of sarcoma CC5 development in maximally deprived hosts was significantly greater (7/19) than in normal controls (1/16) (P is less than 0.05), but the majority of rats (58%) did not succomb to tumour outgrowth. In the case of a third neoplasm--a spontaneously metastasizing fibrosarcoma (P8)--the effect of BCG on primary tumour development was comparable in normal and deprived recipients and was limited to temporary arrest as distinct from complete inhibition. Assessment of the influence of BCG on lung metastases was more complex since the extent of metastatic disease from subcutaneous tumour cells alone was greater in deprived rats than in normal rats. It is concluded that T-cell participation is not a major requirement for BCG contact-induced inhibition in this system and some implications for the mechanism of action are discussed.

Leucocytotoxicity in malignant and non-malignant colonic diseases

The survival of cells from five different cultures of allogeneic malignant colonic carcinoma, two from normal adult colonic epithelium and eight from foetal colonic epithelium in the presence of leucocytes from patients with neoplastic and inflammatory disorders of the colon has been compared. Cytotoxicity assessed by the reduction of the number of adherent target cells in microplate wells compared with those surviving in wells treated with tissue culture medium alone was observed with leucocytes from donors in all categories examined including those from individuals without any known abnormality. Patients with ulcerative colitis were the only group to reveal consistent reactivity against cultures derived from all three sources, an observation which may reflect sensitization to organ-related antigens in this disease. In contrast, leucocytes from patients with bowel neoplasia showed reactivity for cells derived from colon carcinoma tissue, which was comparable to that of healthy donors. Evidence for tumour-specific cytotoxicity was therefore lacking in this study. It is suggested that the detection of tumour-associated antigens on cultured cells may be limited by a number of factors of which the wide variation in reactivity among controls and unspecified nature of the target cells are likely to be of greatest importance.

Fatal disseminated adenovirus infection in a renal transplant recipient

A 61 year old woman died of diffuse interstitial adenovirus pneumonia 55 days after receiving a cadaveric renal allograft. The adenovirus was serologically distinct from the 33 known human adenovirus serotypes and appears to represent a new human adenovirus. Pathologic and virological findings indicate that the pneumonia was only one manifestation of a disseminated infection, the source of which may have been a latent adenovirus infection preexisting in the donor kidney. The establishment of the etiologic diagnosis in this case, which was complicated by the presence of oculocutaneous and esophageal herpes simplex virus infection as well as focal pulmonary aspergillosis, required coordinated histopathologic and virological investigation. Our findings demonstrate that severe viral infections in transplant recipients are not caused exclusively by members of the herpesvirus group.

PHA stimulation of separated human lymphocyte populations

Lymphocyte preparations from peripheral blood and tonsils were separated into populations enriched with T or B cells by formation of rosettes with SRBC and separation of the rosette-forming and non-rosette-forming populations. T cell-enriched populations were also prepared by nylon column filtration. Using these methods preparations were obtained which comprised 80--95% T or B lymphocytes as determined by E-rosette formation and surface immunoglobulin (Ig) staining. PHA responsiveness, measured by [3H]thymidine incorporation, varied between relatively wide limits and was critically dependent on the degree of separation obtained. Relatively pure B-cell populations (less than 12% T cells) from blood and tonsils gave low PHA responses while preparations from blood still containing 24--38% T cells gave responses equal to or even greater than those of unseparated controls (60--78% T cells). T cell-enriched populations (80--86% T cells) responded to an equal or greater degree than controls but more efficient separation (greater than 90% T cells) resulted in markedly reduced stimulation. There was thus no simple correlation between the degree of phytomitogen-induced transformation and the number of T cells present. It is concluded that the low response of relatively pure T-cell populations may be due to depletion of B cells or non-lymphoid cells (or both) during the separation procedures. These observations have implications for the use of PHA stimulation as a measure of T-cell activity in mixed populations such as those of human peripheral blood leucocytes.

Tumour inhibition mediated by BCG in immunosuppressed rats

Two rat sarcomas (CC5 and P7) which grow progressively on transplantation into normal syngeneic hosts failed to develop when injected in admixture with the Glaxo strain of Bacillus Calmette-Guérin (BCG). Under comparable conditions, the local development of a third neoplasm (P8) was temporarily inhibited and the number of pulmonary metastases significantly reduced. Experiments were undertaken to determine the extent to which the anti-tumor action of BCG required an immunocompetent host. Rats were immunosuppressed by sub-lethal whole-body irradiation (450 R), with or without prior thymectomy and challenged with inocula of mixed BCG and tumour cells when their capacity to respond to bacterial, tumour and unrelated antigens was maximally depressed. In non-sensitized immunosuppressed rats, the ability of BCG to limit tumour outgrowth was abrogated only in the case of sarcoma CC5. For this neoplasm, immunogenic in syngeneic hosts by conventional criteria, there was a statistically significant difference in the number of tumours in immunosuppressed rats (51%) compared with non-sensitized immunocompetent controls (6%). Presensitization to either bacterial or tumour antigens, prior to thymectomy and/or irradiation, fully restored the tumour-inhibitory capacity of BCG. By contrast, sarcoma P7 was not significantly less susceptible to BCG-induced regression in non-sensitized immunosuppressed rats than in nonsensitized normal rats; and sarcoma P8 similarly failed to reveal any significant differences in susceptibility to BCG affecting primary or secondary tumour development. It is concluded that tumours may vary widely in their sensitivity to host reactions aroused by BCG. Certain neoplasms, exemplified by sarcoma CC5, require participation of an immune reaction of delayed hypersensitivity type for optimal destruction at BCG sites, while for others (e.g. sarcoma P7) an immunoreactive component of this type is not essential. By contrast, a third category of tumour (e.g. sarcoma P8) is relatively resistant to host reactions induced by the mycobacteria. An important component of BCG-mediated tumour inhibition is not dependent on an immunologically intact host.

Cell surface antigen expression on chemically induced murine leukaemias

The immunogenicity of murine leukaemias induced by chemical carcinogens or irradiation in C57Bl or (C57Bl times DBA2) F1 hybrid mice has been studied in vivo by transplantation and in vitro by indirect membrane immunofluorescence (IF) using syngeneic immune or allogeneic immune antisera. Two of 5 leukaemias tested for immunogenicity by assessment of the capacity of syngeneic mice specifically immunized with irradiated (3 Krad) cells to reject small challenge inocula (10(3)-10(4) cells) displayed weak neoantigenicity while 3 were non-immunogenic by this criterion. Antibodies directed against cell-surface antigens of the immunizing cells of 7 leukaemias were not detectable by immunofluorescence tests using sera from the respective immunized mice. H-2 histocompatibility antigens readily identified on normal lymphoid cells using reference Balb/c anti-C57Bl (H-2d anti-H-2b) alloantisera could neither be detected on the majority of transplanted leukaemias nor on 9 primary leukaemias in C57Bl mice induced by N-butyl-N-nitrosourea (BNU). Two of the transplanted leukaemias showed greatly diminished capacity for absorption of alloantibody compared with normal spleen cells. Transplantation to H-2 different recipients, in which the leukaemic cells were invariably rejected, generated a strong humoral antibody response, which was demonstrable against normal lymphoid cells. Failure to demonstrate significant antibody binding by indirect immunofluroescence tests with immune sera, or by absorption, is presented as evidency that H-2 antigen expression is substantially modified on BNU induced leukaemia cells. These findings have implications for the detection of tumour neoantigens on chemically induced leukaemias.

Cell-mediated cytotoxicity to human pulmonary neoplasms

Peripheral blood leukocytes from patients with confirmed pulmonary neoplasia were tested for cytotoxicity against cultured cells derived from lung tumours of various histological types, foetal and normal adult lung tissue and tumours arising in organs other than the lung. Leukocytes from 73 percent of patients were cytotoxic for lung-tumour derived cells compared with age- and sex-matched normal donors, while the frequencies of reactivity against normal adult lung-derived cells and cells from unrelated tumours (e.g. bladder, colon, breast) were 42 percent and 18 percent respectively. Leukocytes from lung cancer patients were also cytotoxic for cells derived from foetal lung but susceptibility to cytolysis was variable, cells from 13- and 14-week embryos revealing greatest reactivity (88 percent). Leukocytes from patients with a variety of tumours of non-pulmonary origin or with non-malignant conditions (including respiratory disorders) were also reactive with lung-tumour-derived target cells but with a lower overall frequency (35 percent) than those from lung-cancer patients. The significance of these cytotoxicity data for the existence of tumour-specific host immunoreactivity in lung neoplasia is discussed.

Inhibition of mitogen mediated lymphocyte blastogenesis by adenosine

The effect of adenosine on the proliferative response of human peripheral circulating lymphocytes to stimulation by concanavalin A, phytohemagglutinin and pokeweed mitogen was evaluated. Increasing concentrations of adenosine substantially inhibited mitogen mediated lymphocyte blastogenesis. Erythro-9(2-hydroxyl-3-nonyl) adenine. HCl enhanced the inhibitory effect of adenosine. Inosine, the deamination product of adenosine, had an inhibitory effect which was less than that of adenosine. Inhibition by adenosine may be relevant to the normal regulation of immune function and may account in part for the pathophysiological relationship between severe combined immunodeficiency disease and adenosine deaminase deficiency.

Studies on the mechanisms of chemical leukaemogenesis

Following a single injection of MNU into "intact" mice, a high incidence of leukaemia (90%) is obtained, with a 50% induction time of 200 days. Immunological studies indicate that the θ antigen is expressed on the leukaemic cells. Thymectomized MNU treated mice had a 50% induction time of 500 days, and the incidence was somewhat lower. Leukaemias failed to develop in MNU treated T lymphocyte deficient animals and in lethally irradiated, or thymectomized lethally irradiated mice reconstituted with MNU treated bone marrow. It is suggested that the T lymphocytes rather than the haemopoietic stem cells or pre-T cells are the "target cells" in MNU leukaemogenesis.

Antigens of tumours induced by naturally occurring murine sarcoma virus (MSV-FBJ). II. Detection of cell-surface antigens by indirect membrane immunofluorescence

Cell surface antigens expressed by cells transformed in vivo by FBJ virus, a wild type murine sarcoma virus (MSV) complex derived from a spontaneously arising sarcoma in a CF1 mouse, have been studied by indirect membrane immunofluorescence (MIF). Using mouse antisera raised by immunization of syngeneic CBA mice with transplanted FBJ sarcomata an antigen common to all FBJ tumours was detected which was also present on Gross (G) antigen positive tissues, viz. leukaemic and preleukaemic AKR lymphoid cells, but absent from the tissues of mice of G negative strains. Failure to demonstrate antigenic cross-reactivity in reciprocal MIF tests using FBJ immune sera and antisera to MSV-H (Harvey), an MSV isolate of Friend-Moloney-Rauscher (FMR) sub-group specificity, established the virus type-specificity of antigens expressed by sarcoma cells transformed by the respective MSV.The presence of a cellular antigen with G specificity on FBJ sarcoma cells was confirmed in tests with aged exbreeding C57B1 antisera containing naturally occurring G antibody lacking significant virus neutralizing activity. However, evidence for a "sarcoma-non-leukaemia" antigen on cells transformed by MSV-FBJ was not obtained since absorption studies failed to reveal any specificity on FBJ sarcoma cells which was not also present on AKR leukaemic tissues.It is suggested that the major humoral component of the immune response to FBJ sarcoma cells is evoked against antigens specified by the associated non-pathogenic leukaemia virus (MLV-FBJ) and the relationship of antigens demonstrated by MIF to those detected previously by complement fixation (CF) and tumour rejection tests is discussed.

Antigens of tumours induced by naturally occurring murine sarcoma virus (MSV-FBJ). I. Detection of group and type specific antigens by complement fixation

Antigens associated with cells transformed in vivo by FBJ virus, a wild type murine sarcoma virus (MSV) complex originating from a spontaneously arising osteosarcoma in a CF1 mouse, have been partially characterized by complement fixation (CF). Using rat antisera against antigens specified by Gross leukaemia virus (GLV) the group specific (gs) antigen of C-type RNA murine tumour viruses was demonstrated in FBJ tumours as well as in GLV rat leukaemias, AKR lymphomata and sarcomata induced by MSV-H (Harvey), an MSV isolate of Friend-Moloney-Rauscher (FMR) subgroup specificity. Using mouse antisera against antigens present in FBJ cells the Gross (G) or wild type specificity of FBJ tumours was demonstrated by cross reactivity with antigens expressed on normal AKR lymphoid tissues and leukaemias. These antigens were absent from MSV-H induced sarcomata and in reciprocal tests mouse antisera to MSV-H failed to react with antigens present in FBJ tumour cells. No distinction between cellular and virion antigens expressed by FBJ cells was possible by CF although evidence for a cellular antigen with G specificity was obtained in tests using aged C57B1 antiserum containing a naturally occurring G antibody lacking significant virus neutralizing capacity. However, the likelihood that mouse FBJ antisera contain antibodies to type specific viral envelope antigens (VEA) as well as cellular antigen is discussed.

Immunogenicity of rat hepatoma membrane fractions

The principal expression of immunity elicited in syngeneic rats immunized with rat hepatoma membrane fractions was the development of a tumour specific antibody response. This antibody was demonstrable by membrane immunofluorescence staining of viable hepatoma cells in suspension and the sera exhibited complement dependent cytotoxicity for cultured hepatoma cells. In the absence of complement, however, membrane immune sera were highly "blocking", protecting plated hepatoma cells from attack by sensitized lymph node cells. The cell mediated immune response elicited by hepatoma membrane immunization was weak, as evaluated by the colony inhibitory activity of lymph node cells for hepatoma cells in vitro or the adoptive transfer of immunity with peritoneal exudate cells. Correlated with this overall pattern of immune response, membrane immunization did not elicit tumour rejection reactions. These findings are relevant to current views that humoral factors operate antagonistically to limit cell mediated immunity to tumours. A further relevant feature was the observation that membrane immunization, eliciting a prominent humoral immune reaction, conditioned the recipients so that they subsequently failed to elicit a tumour rejection immunity on treatment with irradiated tumour cells.