ISOLATION OF VIRUSES FROM LEUKAEMIC PATIENTS

Do mycoplasmas cause human cancer?

A linkage between mycoplasmas and malignancy was mainly proposed in the 1960s when human-associated mycoplasmas were becoming of interest given the novel characterization of the human respiratory pathogen Mycoplasma pneumoniae. Associations with leukemia and other malignancies, however, were largely ascribed to tissue-culture contamination, which is now recognized as a significant potential problem in molecular biology circles. A few epidemiological studies, however, continue to raise concern over such a linkage. As well, in vitro data have demonstrated the potential for some mycoplasmas to induce karyotypic changes and malignant transformation during chronic tissue-culture infestation. As cellular and molecular mechanisms for such transformation become studied, a resurgence of interest in this area is inevitable. A role for mycoplasmas in malignancy of any sort is conjectural, but there remains a need to continue with focussed epidemiological and laboratory investigations.Key words: mycoplasma, cancer, oncogenesis, leukemia.

Lymphocyte activation by various Mycoplasma strains and species

The capacity of various mycoplasma strains and species to induce lymphocyte transformation in vitro was studied. Of six strains of Mycoplasma pulmonis studied, five displayed mitogenic activity with rat lymphocytes. Among those M. pulmonis strains, our MP15 isolate and the Negroni strain exhibited particularly potent mitogenic capacity. The murine mycoplasmas M. neurolyticum and M. arthritidis shared this mitogenicity for rat lymphocytes. However, the human mycoplasmas M. fermentans, M. pneumoniae, M. hominis, M. orale, and Acholeplasma laidlawii did not activate rat lymphocytes. Lymphocytes obtained from germfree rats were activated to the same extent as those from animals bred under conventional conditions. The mitogenic potency exhibited by mycoplasma was not restricted to infective microorganisms, and preparations of killed mycoplasma particles exerted an extensive lymphocyte transformation. The data show that the mitogenic activity of mycoplasmas is not confined to a single mycoplasma isolate and that it acts in a nonspecific manner.

Mycoplasmas and cell cultures

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Relation between mycoplasmas and leukaemia and related diseases

Forty-five bone marrow specimens from leukaemia patients and 40 marrows from nonleukaemia patients were cultured for mycoplasmas. No mycoplasmas were isolated. Sera from patients with leukaemia or reticuloses and from non-leukaemic subjects were examined for antibodies to the Negroni and 880 strains of Mycoplasma pulmonis and also to the K7, K10, and prototype (PG18) strains of M. fermentans. No significant differences were observed between the two groups of patients with respect to antibodies to these mycoplasmas. These findings support those of the majority of other workers in failing to show any relationship between mycoplasmas and neoplastic disease in man.

Identification of Mycoplasma and other microorganisms by polyacrylamide-gel electrophoresis of cell proteins

The proteins of Mycoplasma cells of various species produce highly reproducible and species-specific electrophoretic patterns in polyacrylamide gels containing 5 m urea and 35% acetic acid. These electrophoretic patterns can be used for the rapid identification and classification of Mycoplasma. Preliminary results indicate that this method may also be used for the identification and classification of other microorganisms.

The Relationship Between A Rodent Mycoplasma, Mycoplasma Pulmonis, and Certain Mycoplasmas Isolated From Tissue Cultures Inoculated with Material from Patients With Leukaemia

Summary

The relationship between Negroni and strain 880 mycoplasmas, isolated from tissue cultures inoculated with material from leukaemic patients, and a rodent pathogen, Mycoplasma polmonis, were studied in detail. The close relationship previously reported between these strains was confirmed but some serological differences were noted. The importance of these differences in the classification of the organisms is discussed.

Growth inhibition test for identification of Mycoplasma species utilizing dried antiserum-impregnated paper discs

The growth inhibition test for identifying Mycoplasma species has been modified by drying antibody-impregnated paper discs at 5 C. When stored at -20 C, these discs have been found to retain their inhibitory activity for longer than 7 months. Since these discs can be stored for long period of time, significant advantages over present methods result. When, for example, discs are arranged on a ring, a single test can be used for the identification of an unknown human species. Valuable antisera can be distributed to other laboratories on paper discs in much less volume than can fluid antiserum. Considerable savings of time result from prior preparation of many discs that can then be stored and used over a long period of time. The growth-inhibiting antibody is stable, and the activity is not enhanced by a heat-labile accessory factor from fresh guinea pig serum which increases the antibody titer in the metabolic inhibition test.

Effect of mycoplasma on interferon production and interferon assay in cell cultures

Armstrong, D. (The Children's Hospital of Philadelphia, Philadelphia, Pa.), and K. Paucker. Effect of mycoplasma on interferon production and interferon assay in cell cultures. J. Bacteriol. 92:97-101. 1966.-The influence of mycoplasma on the production and action of interferon was studied in cultures of both L and human embryonic kidney (HEK) cells. Mycoplasma hominis 1, the Negroni agent, and the F12 mycoplasma were used for infection of L cells, and M. hominis 1 and M. pneumoniae for inoculation of HEK cells. All strains were capable of multiplication in the culture systems employed. None produced detectable levels of interferon, and responsiveness of the cells to induction of interferon by virus remained unaltered. Infection with mycoplasma did not impair the sensitivity of the cells to the action of interferon, nor was the replication of vesicular stomatitis virus noticeably diminished.

Compraison of mycoplasmas associated with human tumors, leukemia, and tissue cultures

Leach, R. H. (Wellcome Research Laboratories, Beckenham, Kent, England), and M. Butler. Comparison of mycoplasmas associated with human tumors, leukemia, and tissue cultures. J. Bacteriol. 91:934-941. 1966.-Mycoplasmas originally isolated by various workers from tissue cultures prepared from or inoculated with tumor or leukemic cells fell into four groups; each related to existing species or serotypes. These were Mycoplasma pulmonis, M. fermentans, M. hominis, and the GDL serotype, the last two being well known as contaminants of uninoculated cell lines. All the test strains were able to grow well in certain tissue cultures, and some caused cytopathic effects and acidity. These observations are discussed in terms of the relationship of these strains to the malignant tissues with which they were originally associated. The variable results obtained in certain biological tests on these strains emphasized the need for standardization of the conditions under which such tests may be employed to assist in identification of Mycoplasma species.

Etiology of leukemia. A review

A variety of factors probably are etiologically involved in leukemia, not only in different cases but also within individual cases. Abnormalities of chromosomes have been found in various types of leukemia. Whether these chromosomal alterations are primary or secondary is undetermined, but it is likely that they are at least contributory in the development of leukemia. There is an increasing body of evidence incriminating viruses in leukemogenesis in man, and they may be a factor in all cases. Certain chemicals may be important etiologic factors in a few cases. Many different studies have established that ionizing radiation in large doses may be leukemogenic. Whether small doses of irradiation are dangerous has not been demonstrated.

A colour test for the measurement of antibody to certain mycoplasma species based upon the inhibition of acid production

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