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Infection and immunology
Published in Jagdish M. Gupta, John Beveridge, MCQs in Paediatrics, 2020
Jagdish M. Gupta, John Beveridge
5.9. Which of the following statements about primary tuberculosis is/are correct?The primary focus in the lung usually cavitates.Symptoms from primary tuberculosis mostly arise from enlargement of the draining lymph nodes.Some degree of blood-borne dissemination occurs with most cases of primary tuberculosis.Sputum positive for acid-fast bacilli (AFB) is required before making a diagnosis of primary tuberculosis.Most cases of miliary tuberculosis and tuberculous meningitis occur within 1 year of initial infection with tuberculosis.
Pulmonary Tuberculosis
Published in Lloyd N. Friedman, Martin Dedicoat, Peter D. O. Davies, Clinical Tuberculosis, 2020
Charles S. Dela Cruz, Barbara Seaworth, Graham Bothamley
Primary tuberculosis (TB) is the disease that occurs when there is no existing immune response to Mycobacterium tuberculosis. These forms of TB occur, therefore, in children who have been recently exposed to an infectious case,1,2 in adults with immunosuppression, for example due to HIV3 and the use of anti-TNF inhibitors,4 and in the elderly where there is waning immunity.5 They may also occur in the rare and atypical forms of TB in those with deficiencies in interferon-γ and IL-12 and their receptors and pathways.6
The respiratory system
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
Primary tuberculosis may be asymptomatic but there can be a vague illness with cough, wheeze, and erythema nodosum. Lymphadenopathy compresses bronchi, causing segmental or lobar collapse. If chronic this causes bronchiectasis, usually in the middle lobe (Brock's syndrome).
Mycobacterium tuberculosis infection of an intralobar pulmonary sequestration
Published in Baylor University Medical Center Proceedings, 2022
Anila Vasireddy, Aadithiyavikram Venkatesan, Akhilesh Gonuguntla, Revanth Maramreddy, Guruprasad D. Rai, Ganesh S. Kamath, Arvind K. Bishnoi
Most patients with ILS are asymptomatic. However, inadequate drainage due to poor communication with normal pulmonary tissue enables optimal conditions for bacteria to proliferate.4 Hence, intervention is necessary, as the ILS may serve as a nidus for future recurrent infections.5 The most common organisms involved include Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus. Although ILS can mimic primary tuberculosis as it most frequently occurs in the left lower lobe,6,7Mycobacterium tuberculosis infection of the sequestered lung tissue has rarely been reported.4,8M. tuberculosis, in particular, potentially favors colonizing sequestrated tissue due to the high arterial blood flow velocities that deliver highly oxygenated systemic blood via the anomalous artery.4 If tuberculosis involves only the sequestered pulmonary tissue, it is imperative to surgically remove the M. tuberculosis focus to prevent potential dissemination.8
Role of Regulatory T Cells in Tubercular Uveitis
Published in Ocular Immunology and Inflammation, 2018
Ravi K. Sharma, Amod Gupta, Shivali Kamal, Reema Bansal, Nirbhai Singh, Kusum Sharma, Sonia Virk, Naresh Sachdeva
Tubercular uveitis is commonly proposed as a disease of immune dysregulation, where attack by M. tuberculosis may worsen the presentation of a subject.18 In a usual primary infection, such as pulmonary tuberculosis, tubercular antigens are presented to CD4+ T cells leading to upregulation of IFN-γ, characteristic of Th1 response.19 In addition to Th1 cells, studies have also reported that the frequencies of both polyclonal and antigen specific Th17 cells increase during primary tuberculosis.20–26 Therefore, initial preponderance of both Th1 and Th17 cells leads to a proinflammatory response, until the mycobacterial modulatory factors come into play. One such major factor, which is effective in controlling local inflammatory responses is Tregs, whose numbers also increase during primary tuberculosis.27,28 This increase in Tregs creates an immunosuppressed environment permitting bacteria to replicate easily and facilitate disease progression. However, the ocular environment being immunologically sequestered may respond differently during tubercular infection. Furthermore, tubercular uveitis is usually not associated with extraocular disease, the immune responses may vary from those in primary tuberculosis. In this context, we investigated T cell immunology in tubercular uveitis in different compartments, including assessment of T cell phenotype in peripheral blood, cytokine milieu in the ocular chamber, proinflammatory potential of Th1 and Th17 cells and suppressive abilities of Tregs in vitro. To the best of our knowledge, this study is the first of its kind to examine the role of Tregs and proinflammatory T cells in tubercular uveitis. Collectively, our results indicate that a decrease in peripheral Treg frequency along with reduced expression of TGF-β and IL-2Rα contribute to heightened proinflammatory responses that manifest at an ocular level in patients with tubercular uveitis.