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PubMed1990

Differential induction of bone marrow macrophage proliferation by mycoplasmas involves granulocyte-macrophage colony-stimulating factor.

We have studied the ability of three different Mycoplasma species to induce proliferation of bone marrow-derived macrophages (BMM). We observed a significant mitogenic effect when BMM cells from BALB/c, DBA/2J, SJL, and C57BL/6 mice were incubated with membranes derived from Mycoplasma arginini or M. arthritidis but not when they were incubated with an equivalent amount of M. pulmonis membrane. We also determined that pretreatment of mycoplasma membrane preparations with papain eliminated the ability of these preparations to induce BMM proliferation. To determine whether these membrane fractions acted indirectly by stimulating the production of soluble factors known to stimulate proliferation of BMM cells, we performed blocking studies with antibodies directed against colony-stimulating factor 1 (CSF-1), interleukin-3 (IL-3), and granulocyte-macrophage colony-stimulating factor. Our results indicate that antibodies directed against either CSF-1 or IL-3 failed to block mycoplasma-initiated proliferation of BMM cells. However, when anti-GM-CSF was added to proliferative cultures at the time of initiation, we saw a dose-dependent reduction of mycoplasma-initiated proliferation. We conclude that the ability of mycoplasma membranes to initiate the proliferation of BMM is not shared by all species of mycoplasma and that it involves the production of GM-CSF by an as yet undetermined cell.

Animals↗

PubMed2005

Identification and characterization of human surfactant protein A binding protein of Mycoplasma pneumoniae.

Mycoplasma pneumoniae infections represent a major primary cause of human respiratory diseases, exacerbate other respiratory disorders, and are associated with extrapulmonary pathologies. Cytadherence is a critical step in mycoplasma colonization, aided by a network of mycoplasma adhesins and cytadherence accessory proteins which mediate binding to host cell receptors. Furthermore, the respiratory mucosa is enriched with extracellular matrix components, including surfactant proteins, fibronectin, and mucin, which provide additional in vivo targets for mycoplasma parasitism. In this study we describe interactions between M. pneumoniae and human surfactant protein-A (hSP-A). Initially, we found that viable M. pneumoniae cells bound to immobilized hSP-A in a dose- and calcium (Ca(2+))-dependent manner. Mild trypsin treatment of intact mycoplasmas reduced binding markedly (80 to 90%) implicating a surface-associated mycoplasma protein(s). Using hSP-A-coupled Sepharose affinity chromatography and polyacrylamide gel electrophoresis, we identified a 65-kDa hSP-A binding protein of M. pneumoniae. The presence of Ca(2+) enhanced binding of the 65-kDa protein to hSP-A, which was reduced by the divalent cation-chelating agent, EDTA. The 65-kDa hSP-A binding protein of M. pneumoniae was identified by sequence analysis as a novel protein (MPN372) possessing a putative S1-like subunit of pertussis toxin at the amino terminus (amino acids 1 to 226), with the remaining amino acids (227 to 591) exhibiting no homology with other subunits of pertussis toxin, other known toxins, or any reported proteins. Recombinant MPN372 (MPN372) bound to hSP-A in a dose-dependent manner, which was markedly reduced by preincubation with mouse recombinant MPN372 antisera. Also, adherence of viable M. pneumoniae cells to hSP-A was inhibited by recombinant MPN372 antisera, demonstrating that MPN372, a previously designated hypothetical protein, is surface exposed and mediates mycoplasma attachment to hSP-A.

Amino Acid Sequence↗

PubMed1987

Activities of oxidative enzymes in mycoplasmas.

The activities of several oxidoreductases were measured in three fermentative and two nonfermentative Mycoplasma species that were grown under aerobic or anaerobic conditions. Acholeplasma laidlawii MG, Mycoplasma hyorhinis GDL, and Mycoplasma pneumoniae FH had very high apparent activities of pyruvate dehydrogenase and pyruvate dehydrogenase complex compared with the activities of mammalian fibroblasts or human platelet-enriched preparations, while Mycoplasma salivarium VV and Mycoplasma arthritidis 07 had very low apparent activities of these two enzymes. Strictly anaerobic growth diminished both enzymatic activities. The activity of alpha-ketoglutarate dehydrogenase complex was minimal in all five mycoplasmas that were grown under aerobic conditions, anaerobic conditions, or both. All the mycoplasmas that were examined exhibited lactate dehydrogenase and NADH-dichlorophenol indophenol oxidoreductase activities. The properties of mycoplasmal pyruvate dehydrogenase complex suggest that it differs from the mammalian enzyme.

Arsenic↗

PubMed1965

Sedimentation counting and morphology of Mycoplasma.

Clark, Harold W. (The George Washington University School of Medicine, Washington, D.C.). Sedimentation counting and morphology of Mycoplasma. J. Bacteriol. 90:1373-1386. 1965.-The sedimentation technique for counting viral particles was applied to the quantitation and morphological identification of Mycoplasma in broth cultures. Mycoplasma, apparently in their native form, firmly adhered to the surface, when sedimented on glass cover slips or onto electron microscope grids. The sedimented cover slip preparations stained with crystal violet could be readily counted in the light microscope. The cultures sedimented onto electron microscope grids were readily counted at low magnification and provided excellent preparations for morphological examination at higher magnifications. It was found that air-dried Mycoplasma particles were enlarged considerably because of excessive flattening. Fixation of sedimented Mycoplasma particles in diluted OsO(4) prior to air drying yielded a more realistic morphology, with various sizes and shapes in the stages of the growth cycle exhibited. A new technique of differentially staining Mycoplasma colonies on agar plates was developed to facilitate the quantitation of viable colony-forming units for comparison with total counts. The use of plastic or Parafilm gaskets for dry mounting was developed to facilitate the handling and examination of the stained cover slip preparations. The results of this investigation indicated that the growth cycle of some Mycoplasma species includes a stage of hexadic fission with the cleavage of minimal reproductive units (less than 100 mmu) containing a limited deoxyribonucleic acid genetic coding molecule (approximately 4 x 10(6)).

Bacteriological Techniques↗

PubMed1969

Utilization of neuraminic acid receptors by mycoplasmas.

Erythrocytes and H-HeLa cells were treated with neuraminidase and then compared with untreated cells for their ability to adsorb to mycoplasma colonies or be agglutinated by suspensions of the mycoplasmas. Of the 17 mycoplasma serotypes examined, only 4 were found to use neuraminic acid receptors; these were Mycoplasma pneumoniae, M. gallisepticum, M. synoviae, and mycoplasma WR1. Not all strains of a serotype behaved alike. Thus, removal of receptors on erythrocytes for one strain of M. gallisepticum required at least 100 times the concentration of neuraminidase needed to remove them for another strain. The mechanism of attachment of erythrocytes to mycoplasma colonies does not appear to be the same as that for attachment to mycoplasmas in suspension.

Adsorption↗

PubMed2005

Evaluation of amplified rDNA restriction analysis (ARDRA) for the identification of Mycoplasma species.

BACKGROUND: Mycoplasmas are present worldwide in a large number of animal hosts. Due to their small genome and parasitic lifestyle, Mycoplasma spp. require complex isolation media. Nevertheless, already over 100 different species have been identified and characterized and their number increases as more hosts are sampled. We studied the applicability of amplified rDNA restriction analysis (ARDRA) for the identification of all 116 acknowledged Mycoplasma species and subspecies. METHODS: Based upon available 16S rDNA sequences, we calculated and compared theoretical ARDRA profiles. To check the validity of these theoretically calculated profiles, we performed ARDRA on 60 strains of 27 different species and subspecies of the genus Mycoplasma. RESULTS: In silico digestion with the restriction endonuclease AluI (AG--CT) was found to be most discriminative and generated from 3 to 13 fragments depending on the Mycoplasma species. Although 73 Mycoplasma species could be differentiated using AluI, other species gave undistinguishable patterns. For these, an additional restriction digestion, typically with BfaI (C--TAG) or HpyF10VI (GCNNNNN--NNGC), was needed for a final identification. All in vitro obtained restriction profiles were in accordance with the calculated fragments based on only one 16S rDNA sequence, except for two isolates of M. columbinum and two isolates of the M. mycoides cluster, for which correct ARDRA profiles were only obtained if the sequences of both rrn operons were taken into account. CONCLUSION: Theoretically, restriction digestion of the amplified rDNA was found to enable differentiation of all described Mycoplasma species and this could be confirmed by application of ARDRA on a total of 27 species and subspecies.

Animals↗

PubMed2006

Alteration of gene expression profiles during mycoplasma-induced malignant cell transformation.

BACKGROUND: Mycoplasmas are the smallest microorganisms capable of self-replication. Our previous studies show that some mycoplasmas are able to induce malignant transformation of host mammalian cells. This malignant transformation is a multistage process with the early infection, reversible and irreversible stages, and similar to human tumor development in nature. The purpose of this study is to explore mechanisms for this malignant transformation. METHODS: To better understand mechanisms for this unique process, we examined gene expression profiles of C3H cells at different stages of the mycoplasma-induced transformation using cDNA microarray technology. A total of 1185 genes involved in oncogenesis, apoptosis, cell growth, cell-cycle regulation, DNA repair, etc. were examined. Differences in the expression of these genes were compared and analyzed using the computer software AtlasImage. RESULTS: Among 1185 genes screened, 135 had aberrant expression at the early infection stage, 252 at the reversible stage and 184 at the irreversible stage. At the early infection stage, genes with increased expression (92 genes) were twice more than those with decreased expression (42 genes). The global gene expression at the reversible stage appeared to be more volatile than that at any other stages but still resembled the profile at the early infection stage. The expression profile at the irreversible stage shows a unique pattern of a wide range of expression levels and an increased number of expressing genes, especially the cancer-related genes. Oncogenes and tumor suppressors are a group of molecules that showed significant changes in expression during the transformation. The majority of these changes occurred in the reversible and irreversible stages. A prolonged infection by mycoplasmas lead to the expression of more cancer related genes at the irreversible stage. CONCLUSION: The results indicate that the expression profiles correspond with the phenotypic features of the cells in the mycoplasma induced transformation process. The early mycoplasma infection stage shares a common phenomenon with many other acute infections, genes with increased expression significantly outnumbering those with decreased expression. The reversible stage is a transition stage between benignancy and malignancy at the molecular level. Aberrant expression of oncogenes and tumor repressors plays a key role in mycoplasma-induced malignant transformation.

Animals↗

PubMed2002

Comparative PCR analysis for detection of mycoplasma infections in continuous cell lines.

Mycoplasma contamination of cell lines is one of the major problems in cell culturing. About 15-35% of all cell lines are infected with a limited number of mycoplasma species of predominantly human, swine, or bovine origin. We examined the mycoplasma contamination status in 495 cell cultures by polymerase chain reaction (PCR) assay, microbiological culture method, and deoxyribonucleic acid-ribonucleic acid (DNA-RNA) hybridization, and in 103 cell cultures by PCR and DNA-RNA hybridization, in order to determine the sensitivity and specificity of the PCR assay in routine cell culture. For those two cohorts, results for the three or two assays were concordant in 92 and 91% of the cases, respectively. The sensitivity (detection of true positives) of this PCR detection assay was 86%, and the specificity (detection of true negatives) was 93%, with positive and negative predictive values (probability of correct results) of 73 and 97%, respectively. PCR defined the mycoplasma status with 92% accuracy (detection of true positives and true negatives). The mycoplasma contaminants were speciated by analyzing the PCR amplification fragment using several restriction enzymes. Most of the cultures (47%) were infected with Mycoplasma fermentans, followed by M. hyorhinis (19%), M. orale (10%), M. arginini (9%), Acholeplasma laidlawii (6%), and M. hominis (3%). To sum up, PCR represents a sensitive, specific, accurate, inexpensive, and quick mycoplasma detection assay that is suitable for the routine screening of cell cultures.

Animals↗

PubMed2007

Mycoplasma genomics: tailoring the genome for minimal life requirements through reductive evolution.

Prokaryotic organisms of the genus Mycoplasma are characterized by their small body and genome size containing a 0.6-1.35 M bp genome. The genome is noted for its low G+C frequency ranging from 8-40 mol%. The Mycoplasma genus stems from the class Mollicutes (for soft skin), which lacks the cell walls and external motility appendages often present in other bacteria. To date, there are more than 100 known species of Mycoplasma. 34 species have been partially or completely sequenced. Widely known pathogenic species of Mycoplasma include: M. pneumoniae, causing pneumonia and other respiratory disorders, and M. genitalium, which are involved in pelvic inflammatory disease. Because of their small genome size, Mycoplasmas provide researchers a unique model of the minimal genomic requirements to maintain life. As the number of complete Mycoplasma genomes increase, these organisms become more established, thus laying the foundation for mapping evolutionary development. This manuscript provides an overview and update on Mycoplasma research, with particular focus on current genomics.

Computational Biology↗

PubMed1997

High-level expression of H-ras and c-myc oncogenes in mycoplasma-mediated malignant cell transformation.

C3H mouse embryo cells, which normally have low inherent spontaneous transformation, underwent malignant transformation while chronically infected with Mycoplasma fermentans or Mycoplasma penetrans. This mycoplasma-mediated oncogenic process had long latency (more than 7 weeks of persistent mycoplasmal infection) and showed multistage progression characterized by reversibility and irreversibility of malignant properties upon removal of M. fermentans from culture. Marked expression of H-ras and c-myc mRNA, but not N-myc, src, N-ras, or p53 mRNA, was found in the mycoplasma-transformed C3H cells that exhibited characteristic malignant properties of morphological changes and uncontrolled cell growth. However, at least up to the eleventh week of persistent mycoplasma infection, the marked expression of H-ras or c-myc mRNA in C3H cells depended on continued presence of the mycoplasma in culture. H-ras or c-myc mRNA rapidly declined to the undetectable low levels of nontransformed parental C3H cells, and all malignant properties of the once-fully-transformed C3H cells quickly reversed, if M. fermentans was eradicated from culture. In comparison, infection with M. penetrans for 7 or 11 weeks also induced a high level of H-ras, but not c-myc, mRNA expression in C3H cells. Despite having prominent amount of steady-state H-ras mRNA, these M. penetrans-infected C3H cells did not show any sign of malignant transformation. Thus, marked expression of H-ras gene alone was not sufficient to effect transformation in C3H cells. Interestingly, after a further prolonged (18 weeks) infection with either M. fermentans or M. penetrans, C3H cells revealed prominent chromosomal changes, expressed constitutively (with or without the presence of the transforming mycoplasmas) at high levels of both H-ras and c-myc mRNA and became permanently transformed. These cells were able to form tumors in animals.

Animals↗

PubMedDate not supplied

Falsification of tetrazolium dye (MTT) based cytotoxicity assay results due to mycoplasma contamination of cell cultures.

Mycoplasma contamination of cell cultures is a frequently observed problem. Due to the inconspicuous growth in cell cultures, periodical screening procedures represent the only protection. Many influences of mycoplasma on cell culture parameters have been described. We addressed the question of whether mycoplasma contamination affects the most frequently used cytotoxicity assay, the tetrazolium based MTT assay. We contaminated C6 glioma cells with mycoplasma and performed MTT assays with doxorubicin, vincristine, etoposide and cisplatinum under various conditions. Contaminated cells demonstrated significant different results when tested with the MTT assay than mycoplasma free controls. Differences were not detectable when cells were counted as toxicity assay. Due to an additional reduction of tetrazolium by mycoplasmas, contaminated cells appeared up to 15 fold resistant to doxorubicin, vincristine and etoposide, but not to cisplatinum. Differences decreased with decreasing drug doses and decreasing plated cell count. Our findings confirm the compelling need for periodical mycoplasma screening, especially when tetrazolium based cytotoxicity assay (MTT) are used.

Animals↗

PubMedDate not supplied

Mycoplasma mycoides subsp. mycoides SC identification by PCR in sperm of seminal vesiculitis-affected bulls.

In this study, by using the polymerase chain reaction (PCR) diagnosis for the detection and identification of Mycoplasma, we investigated mycoplasmas contaminating the semen of yearling bulls affected by seminal vesiculitis. The bulls presented neither subclinical nor clinical contagious bovine pleuropneumonia signs and the complement fixation test for specific antibodies was negative. Furthermore, we have investigated mycoplasmas isolated from semen of healthy breeding bulls of several breeds and origins, which routinely underwent breeding soundness examinations and presented no clinical signs of seminal vesiculitis. We were able to demonstrate mycoplasma infection in all tested samples by i) growth on mycoplasma-specific media and ii) a PCR-based method using a mycoplasma-specific MGSO/GPO1 primer set to amplify the 16S fragment rDNA. In addition, the identification of Mycoplasma species was made by PCR using the MSC1/MSC2 primer set that specifically amplifies M. mycoides subsp. mycoides SC or the MM450/MM451 primer set followed by AsnI digestion analysis in order to identify M. mycoides subsp. mycoides LC. The data presented herein clearly show that M. mycoides subsp. mycoides SC infection was associated with seminal vesiculitis while M. mycoides subsp. mycoides LC was only found in bull semen from healthy control animals. Our findings confirm that the M. mycoides subsp. mycoides SC is shed in the sperm making the ejaculate a valuable biological sample for the isolation of these bacteria from serologically negative animals. Although the pathogenic role of M. bovigenitalium in bull seminal vesiculitis has been established, our clinical findings, semen characteristics, microbiological and bacterial genomic analysis strongly suggest that M. mycoides subsp. mycoides SC may contribute to induce vesicular adenitis in the bull.

Animals↗

PubMed1975

Mycoplasma species recovered from the reproductive tracts of western Canadian cows.

Samples of cervico-vaginal mucus from 633 animals from 110 herds were cultured and yielded the following mycoplasmas: T-strain--88: Mycoplasma bovigenitalium--79, Mycoplasma spp. (Leach Group 7)--7, Acholeplasma laidlawii--4, Mycoplasma bovirhinis--2 and one not typable. Uterine exudates and endometrial scrapings from 80 infertile cows in two herds were examined. Four animals were positive, M. bovigenitalium was isolated three times, A. laidlawii and Mycoplasma arginini once each. Sixty-five normal uterine contents from pregnant cows were examined, one yielded M. bovigenigalium and the same organism was recovered from the fetal kidney. T-strain mycoplasma, M. bovigenitalium and other Mycoplasma spp. appear to be a part of the normal flora of the cervico-vaginal region of clinically normal one and two year old bred heifers in Alberta and Saskatchewan. Although M. arginini was not recovered from the cervico-vaginal region, a single recovery was made from the uterus of an infertile cow.

Animals↗

PubMed2002

[Detection of Mycoplasma hyorhinis in gastric cancer using bio-chip technology].

OBJECTIVE: To determine the prevalence of Mycoplasma hyorhinis in archived paraffin-embedded gastric cancer tissue and to find whether Mycoplasma hyorhinis infection can influence gene expression level in gastric cancer cells. METHODS: A high-dense tissue microarray containing 105 gastric cancer samples, 101 benign margin samples and 62 non-cancerous gastric disease samples resected during operation was constructed. PD4, a specific anti-Mycoplasma-hyorhinis Mab, was used to detect the infection rate in all the samples in the tissue microarrays immunohistochemically. Then, cDNA microarray was used to pinpoint differentially the expressed genes between gastric cancer cell line MGC803 samples with and without Mycoplasma hyorhinis infection. RESULTS: The infection rate of M. hyorhinis was 54.1% 53/98 in gastric cancer samples, 51.7% 45/87 in benign margin samples, and 15.8 % 9/57 in non-cancerous disease samples respectively. The difference of infection rates between gastric cancer and non-cancerous gastric disease was statistically significant (P = 0.001). Highly differentiated adenocarcinomas had more opportunity (84.6%) to be infected with M. hyorhinis than poorly differentiated ones (45.9%)(P < 0.05). Intestinal type of gastric cancers (according to Lauren's classification) got the infection more often than diffused type. About 409 gene expression alterations were detected in 48 000 sites from two gastric cancer cell lines and the expression levels of some genes correlating with cell apoptosis and cell adhesion were down regulated after Mycoplasma hyorhinis infection. CONCLUSION: The infection rate of M. hyorhinis is significantly higher in gastric cancer than in other gastric diseases, thus indicating the association between Mycoplasma infection and gastric cancer. Mycoplasma hyorhinis infection influences the gene expression level in gastric cancer cell line MGC803, which indicates that the infection could have something to do with the process of gastric cancer. The question whether M.hyorhinis has oncogenic potential remains to be elucidated.

Adult↗

PubMed1976

Mycoplasma in biological systems: induction of interferon.

Mycoplasmal infection leads to a variety of effects on host cells both in vivo and in vitro. Among these is the induction of interferon, which has been demonstrated in mycoplasma-infected human and sheep lymphoreticular cell cultures and in mice. Different species and strains of mycoplasma vary in their ability to induce interferon in these experimental models. Several studies have shown that mycoplasmas do not elicit the production of interferon in murine cells in vitro or in non-lymphoreticular cells of other animal species. This may be related to the ability of host cells to take up mycoplasmas or to mycoplasma-associated products, such as mycoplasmal viruses. Initial studies of mixed infections with mycoplasmas and animal viruses in vivo have demonstrated both an inhibition and an enhancement of viral disease, indicating the complex nature of mycoplasma-animal virus interactions.

Animals↗

PubMed2003

Detection and treatment of mycoplasma contamination in cultured cells.

BACKGROUND: Mycoplasmas, the smallest and simplest prokaryotes that reside in endosomes of mammalian cells, are widespread contaminants found in cell cultures. About 30% of all cell cultures, varying from 15 to 80%, are reportedly contaminated with mycoplasmas. Here, we present our experience in successfully detecting and treating mycoplasmal infection in various cell lines. METHODS: The nested polymerase chain reaction (PCR) detection and microscopic examination, including phase-contrast, fluorescent, as well as differential interference contrast, were used for detecting potential mycoplasma contamination of cell lines used in our laboratory. As soon as mycoplasma was identified, antibiotic treatment was initiated. RESULTS: Mycoplasmal contamination was detected in six of 15 cell lines using the nested PCR amplification of mycoplasma DNA, which was further demonstrated using 4, 6-Diamidino-2-phenylindole (DAPI) staining and fluorescent microscopy. Alternate treatment with two antibiotics, macrolide (tiamulin) and tetracycline (minocycline), effectively eliminated mycoplasma, which was validated by both PCR and microscopic studies. CONCLUSIONS: The nested PCR using genomic DNA extracted from cultured cells as templates is a rapid and sensitive method for detecting mycoplasma contamination. Treatment with combined antibiotics can completely eradicate mycoplasmal infection from cultured cells. For the ease of use, PCR and/or DAPI staining appear suitable for detecting potential mycoplasmal contamination in laboratories that rely heavily on the cell culture system.

Anti-Bacterial Agents↗

PubMed2004

[Male urogenital tract mycoplasma infection and drug-resistance evolution].

OBJECTIVE: To investigate the male urogenital tract mycoplasma infection and drug-resistance evolution in 2001 and 2003. METHODS: The results of mycoplasma culture and drug sensitivity tests were explored in 2001 and 2003, and the differences of drug sensitivity between the two years were analysed. RESULTS: Of the 109 mycoplasma positive cases in 2001, 86.2% were infected with Ureaplasma urealyticum (Uu), 3.8% with Mycoplasma hominis (Mh), 10.1% with both Uu and Mh; and of the 134 mycoplasma positive cases in 2003, Uu infection accounted for 79.1%, Mh infection 4.48% and Uu and Mh infection 16.4%. Compared with 2001, the drug-resistance rates to roxithromycin, azithromycin, levofloxacin, ofloxacin and clindamycin rose obviously in 2003; but the drug-resistance rates to josamycin, minomycin and doxycycline did not change significantly. As far as the drug sensitivity rate is concerned, josamycin ranked the first, and doxycycline the second. CONCLUSIONS: Mycoplasma was a high rate of drug-resistance, and the drug sensitivity evolves with the time. Treatment for mycoplasma should be based on the results of drug sensitivity tests. Josamycin can be used as the first choice.

Adolescent↗

PubMed1989

Induction of class II MHC antigen expression in macrophages by Mycoplasma species.

Several different Mycoplasma species have been shown to act as mitogens for either T or B cells and as stimulators of macrophage tumoricidal activity. In this report, we show that at least five different species of Mycoplasma are capable of inducing class II MHC expression on macrophages. We have observed significant induction of class II MHC surface expression on the myelomonocytic cell line, WEHI-3, as early as 24 h after deliberate infection of cultures, reaching maximal levels by 4 days. This induction was also apparent at the mRNA level as assessed by Northern blot analysis by using A alpha, E alpha, and A beta probes. However, unlike many other previously described MHC-inducing agents, mycoplasmas failed to induce class I MHC expression at either the cell surface or mRNA levels. Kinetic analysis revealed that induction of class II mRNA by mycoplasmas was slower than induction by IFN-gamma requiring 24 h rather than 8 h for significant increases to be noted. Induction by mycoplasmas does not require the presence of live organisms and remains active after heat treatment of 90 degrees C for 30 min. We have also demonstrated that mycoplasma infection of primary bone marrow macrophage cultures leads to the induction of both class I and class II genes and, as in the case of WEHI-3, this induction does not require the presence of live organisms. These data indicate that several Mycoplasma species have the capacity to induce class II MHC expression in WEHI-3 and both class I and class II MHC expression in bone marrow macrophage cultures in the absence of any T cell products.

Animals↗