John Stanford

Give us this day our daily germs

Are we sparing the dirt and spoiling our childrens immune systems? The theory that some germs are necessary in developing healthy immune systems is gaining credence as more evidence emerges. It is vital that we find out which germs are needed, when and how, before the increase in diseases attributable to faulty regulation of the immune system (allergies, autoimmunity, inflammatory bowel disease) spirals out of control.

Attachment of Mycobacteria to Fibronectin-coated Surfaces

This report investigates the extent of the expression of fibronectin (FN) binding properties among the mycobacteria and provides preliminary characteristics of the bacterial molecule(s) mediating attachment. Eight BCG substrains, three Mycobacterium tuberculosis strains and four other mycobacterial species all expressed FN-binding capacity. Treatment of organisms with detergent prior to the binding assay destroyed the FN-binding capacity of BCG but not that of Staphylococcus aureus. Trypsin pretreatment eliminated the FN-binding capacity of both BCG and S. aureus. [35S]Methionine-labelled material in supernatants from BCG and M. tuberculosis cultures attached to FN-coated surfaces. These culture supernatants inhibited the attachment of BCG but not S. aureus to FN-coated surfaces. This inhibitory activity of the supernatants was removed by affinity chromatography on FN-Sepharose but was not affected by similar passage over a control column (human serum albumin attached to Sepharose). These results demonstrate that the ability to bind FN is present in all mycobacterial species tested and suggest that attachment is mediated by trypsin-sensitive cell-surface component(s).

Hiv infection alters the production of both type 1 and 2 cytokines but does not induce a polarized type 1 or 2 state

Objective:To test the T-helper (TH)1/TH2 cytokine paradigm in HIV infection. Design and methods:Cytokine profiles in two separate studies of HIV patients and controls are presented: (i) a longitudinal study of HIV patients with CD4 counts > 500 × 106/l tested at three timepoints compared with controls; (ii) a blinded cross-sectional study of controls and patients with high (> 500 × 10/6l) and low (< 500 × 106/l) CD4 counts. Peripheral blood mononuclear cells (PBMC) from patients and controls were tested for the production of two type 1 [interleukin (IL)-2, interferon (IFN)-γ] and two type 2 (IL-4, IL-10) cytokines by enzyme-linked immunosorbent assay. Both spontaneous and mitogen-induced cytokine production was measured. Results:HIV infection was noted to have the following effects on cytokine production: (i) it led to the in vivo activation of type 2 cytokines in a small group of individuals with high CD4 numbers characterized by the spontaneous release of IL-4 and IL-10. Longitudinal data showed high spontaneous IL-4 and IL-10 to be a consistent feature of the patient group (at each timepoint some patients were high producers) but to be variable in a given individual; (ii) HIV infection impaired the ability of PBMC to respond to stimuli (selected for their ability to optimally induce each cytokine) in terms of IL-2, IL-4 and IL-10 production in patients with both high and low CD4 cell counts; and (iii) conversely, HIV infection led to an overproduction of IFN-γ in patients with high CD4 counts; patients with low CD4 produced normal levels of IFN-γ. Conclusions:Our observations did not suggest polarization of the type 1/type 2 cytokine profile in HIV patients. Instead, the data suggested more complex changes to type 1/type 2 cytokine patterns in HIV infection than originally proposed by the TH1/TH2 dichtomy.

Tuberculosis and cancer: parallels in host responses and therapeutic approaches?

Mycobacteria elicit two quite different immune responses. One is protective and is partly based on recognition and lysis of stressed, bacilli-laden cells expressing heat-shock proteins. The other suppresses this recognition and instead leads to indiscriminate necrosis of tissues containing mycobacteria (the Koch phenomenon). The type of response depends on the predominant T-cell maturation pathway, Th1 or Th2, which in turn is determined by priming by prior contact with environmental mycobacteria. Vaccination by BCG induces whichever response the recipient is primed to make, and this is a likely explanation of the variable efficacy of this vaccine in prevention of tuberculosis and therapy of cancer. Thus; BCG is a two-edged sword. We postulate that by using other mycobacterial preparations, such as killed Mycobacterium vaccae, it might be possible to suppress the indiscriminate necrosis and enhance Th1-regulated selective destruction of tumour cells.

Immunotherapy with Mycobacterium vaccae as an addition to chemotherapy for the treatment of pulmonary tuberculosis under difficult conditions in Africa

A study to assess the impact of immunotherapy with Mycobacterium vaccae on the treatment of pulmonary tuberculosis was conducted under existing conditions in Kano, a large city in Northern Nigeria. Whilst it did not quite meet all the criteria of a well-controlled randomized or double-blind trial, the study produced results suggestive of a successful intervention. Immunotherapy with M. vaccae had a beneficial influence on clinical recovery and survival, whether given after 1, 2 or 3 weeks of chemotherapy, according to an assessment made 10-14 months after treatment. Approximately 3 weeks (19.8 days) after the onset of chemotherapy (SHRZ), 73% of the patients who received immunotherapy and 19% of those who received placebo (chemotherapy alone) had become sputum negative by microscopy for acid-fast bacilli (AFB). Similarly, a mean fall in erythrocyte sedimentation rate (ESR) of 25.4 +/- 2.50 mm and 4.0 +/- 2.29 mm was observed in the immunotherapy and placebo recipients respectively, at the same time of assessment. When weight was assessed in the two groups, it was observed that 3 weeks after starting chemotherapy, the recipients of immunotherapy had a mean weight gain of 2.90 +/- 0.24 kg whilst placebo recipients had a mean weight gain of only 0.55 +/- 0.17 kg. These parameters were re-evaluated, 10-14 months later. They showed that 11% of the recipients of the active intervention and 84.6% of placebo recipients still had demonstrable AFB in their sputum. The mean weight gain had increased to 7.91 +/- 1.03 kg and 2.04 +/- 0.94 kg in the immunotherapy and placebo recipients respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of mycobacterial adjuvant-based agents for immunotherapy of cancer

A heat-killed preparation of Mycobacterium vaccae (SRL172) has been shown, in recent studies, to be effective in the treatment of adenocarcinoma of the lung and renal cell cancer. It is postulated that the mechanisms of this form of immunotherapy is, at least in part, due to immune regulation, reflected in the selective enhancement of Th1 and down-regulation of Th2 T cell activity. These beneficial effects are attributed to the ability of adjuvants in the bacterial cell walls to modify and optimise the response to antigens shared by the bacteria and stressed host tissues, resulting in the destruction of cancer cells by programmed cell death or apoptosis. The M. vaccae-induced apoptosis appears to be most effective against carcinomas, perhaps especially those of glandular tissue, in contrast to pyrexia-induced necrosis which is most effective against tumours of mesodermal origin. In view of the great range of adjuvants, especially in the genus Mycobacterium and related genera, it may prove possible to develop a range of immunotherapeutic agents with useful activity against a wide range of cancers.

A longitudinal study of environmental mycobacteria on a farm in south-west England

Soil, stream beds and cattle drinking troughs were sampled every 3 months over 3 years. More than 750 putative mycobacteria were isolated and grouped into more than 50 biotypes pending full identification. Samples from woodland and farmed land yielded fewer isolates per site compared with other terrains (P < 0.05). Some seasonal effects were noted but the greatest difference was between years 1 and 3. This appeared not to be due to differences in temperature, rainfall or experimental procedure, but coincided with the introduction of organic farming practices. In year 3 there was a significant increase in nitrate‐reducing slow growers, both pigmented (P≤ 0.006) and non‐pigmented strains (P≤ 0.002), and a shift in biotypes was noted. In contrast, all fast growers declined with time, as did those slow growers unable to reduce nitrate. Changing farming practice may alter the profile of environmental mycobacteria, which has important implications for the immunological priming of humans and animals.

The Koch phenomenon and the immunopathology of tuberculosis

Tuberculosis kills more than three million people every year, and the problem is rapidly increasing. This is paradoxical when we know that the immune response is perfectly capable of coping with this infection. Before the advent of HIV, only 5% of infected individuals developed disease, and perhaps another 5% did so when T cell function was compromised by old age, stress or protein malnutrition. Therefore 90% of the population was resistant under normal circumstances. Moreover the incidence in the suceptible 10% could be reduced by up to 80% by BCG vaccination in those countries in which the vaccine worked. Why then are we failing to control the rapid increase in tuberculosis?

Immunotherapy with Mycobacterium vaccae in the treatment of tuberculosis in Romania. 2. Chronic or relapsed disease

In this study of 102 patients with culture-positive chronic treatment failure or repeatedly relapsed pulmonary tuberculosis receiving chemotherapy, 56 received an injection of killed Mycobacterium vaccae as immunotherapy after 1 month of treatment. At the start of treatment, there was little difference between those receiving immunotherapy and the 46 patients in the control group receiving chemotherapy alone. Thereafter, the two groups diverged so that 1 yr later, 43 of 56 (77%) patients receiving M. vaccae had a successful outcome, in comparison with 24 of 46 (52%) patients receiving chemotherapy alone (P < 0.02). Successful results were obtained from patients infected with drug-resistant bacilli, 20 of 32 (63%) patients compared with 11 of 25 (44%) patients, respectively, as well as from fully drug-sensitive cases (23 of 24 compared with 12 of 21 patients; P = 0.004). At the final follow-up after 22 months, 13 of 56 patients receiving immunotherapy had an unfavourable outcome compared with 26 of 46 members of the control group (P = 0.0006). During the study, 16 patients died of tuberculosis (six after immunotherapy), and 12 were lost to follow-up. Not only was bacteriological success improved by immunotherapy, chest X-ray showed markedly better resolution of cavities and other radiological lesions, recovery of body weight was improved, and the mean erythrocyte sedimentation rate returned almost to normal (P < 0.001) in comparison with those receiving chemotherapy alone. These changes were seen even in those failing bacteriological cure, suggesting that the immunotherapy had been effective, but that bacilli were replicating in an extracellular situation, protecting them from its effects.

Immunotherapy with Mycobacterium vaccae in the treatment of tuberculosis in Romania. 1. Newly-diagnosed pulmonary disease

In this study, 206 previously untreated patients with sputum culture positive pulmonary tuberculosis were randomized to receive an injection of killed Mycobacterium vaccae as immunotherapy, or of saline as placebo, after 1 month of a 6-month chemotherapeutic regime. Not surprisingly in a disease for which there is good chemotherapy, the difference in numbers which were culture negative at the end of treatment was small, and the final outcome at the latest post-treatment follow-up did not reach statistical significance between the two arms of the study. Nonetheless, those receiving immunotherapy showed better progression in every parameter measured, suggesting faster and more complete cure. Whereas seven of 97 patients receiving immunotherapy required a course of re-treatment and five still had active disease after a mean follow-up of 2 yr, 13 of 109 placebo recipients required re-treatment and nine still had active disease at the end of the study. Only one patient receiving M. vaccae plus chemotherapy died of tuberculosis, compared with four of those receiving chemotherapy alone. A degree of drug resistance was shown by the bacilli cultured from 25 of 175 (14%) patients, and seven of them (4.0%) were multi-drug resistant. Fourteen patients received immunotherapy of whom 13 were cured, including all three of those showing multi-drug resistance. Of the 11 patients with drug resistance in the control group, eight were cured, and one patient with multi-drug-resistant disease died of tuberculosis during re-treatment.