This report of concurrent granulomatous Pneumocystis carinii pneumonia (GPCP) and Mycobacterium xenopi pneumonia (MXIP) in a patient with advanced HIV disease 3–5 weeks after commencing antiretroviral therapy (ART) fits the syndrome of HIV immune reconstitution/restoration disease (IRD). It may also be a unique window into the immunology of granulomatous inflammation.
- granulomatous Pneumocystis carinii pneumonia
- Mycobacterium xenopi pneumonia
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A 35 year old white HIV positive man commenced antiretroviral therapy (ART) with zidovudine, lamivudine, and nelfinavir 7 years after diagnosis (CD4 count 20 cells/ml, viral load 154 000 copies/ml (Chiron III)). Prophylaxis for Pneumocystis carinii pneumonia (PCP) was with nebulised pentamidine. Three weeks after commencing ART, with no prior respiratory symptoms, he developed an unproductive cough. Despite 2 weeks of treatment with amoxicillin, his cough persisted and, although he was well, a chest radiograph 5 weeks after initiating ART showed bilateral apical consolidation (fig 1A). Arterial blood gas tensions on air were normal (Pco2 4.53 kPa, Po2 16.3 kPa, pH 7.468). Bronchoscopic examination after 3 days of treatment with high dose intravenous Septrin showed generalised mucosal inflammation, and the bronchoalveolar lavage (BAL) fluid had scanty Candidaalbicans but was negative for acid fast bacilli and P carinii. Ten days after PCP treatment the apical consolidation improved significantly (fig 1B) but the appearance of a new area of right mid-zone consolidation led to diagnostic biopsy to exclude a malignant process. A percutaneous computed tomographic (CT) guided lung biopsy (left apex, 3 × 20G tissue cores) was undertaken 13 days after admission. The CT scan showed consolidation (fig 1C and D) with multiple small and medium sized pulmonary nodules (many cavitated) in both upper and right middle lobes. Histological examination showed granulomatous PCP (fig 1E and F). Blood culture for M avium complex and polymerase chain reaction for Mtuberculosis were both negative. M xenopi was isolated from the BAL fluid and three sputum specimens after 6 weeks but tissue culture was negative. Precautionary empirical treatment for M tuberculosis with rifampicin, isoniazid, pyrazinamide and ethambutol was commenced after the biopsy finding of granulomatous lung disease but was discontinued after 6 weeks, and non-tuberculous mycobacterial treatment with clarithromycin, ciprofloxacin and rifabutin was started and continued until resolution of the right middle lobe abnormalities 14 months later. The patient remains well on ART with a CD4 count of 510 cells/ml and an undetectable viral load.
Race et al1 reported five patients who, within weeks of commencing ART, developed a systemic syndrome with marked inflammatory reactions to latent infection with M avium complex. All experienced CD4 increments. Such paradoxical hyper-accentuated inflammatory responses to pre-existing or co-existing infections are recognised complications of immune reconstitution following ART; occurring within days to months and invariably associated with CD4 increments, they are collectively known as immune reconstitution/restoration disease (IRD).2 The dynamics of T cell increments following ART is a biphasic phenomenon;3 the first phase (weeks to 6 months) is predominantly of T memory cell redistribution, while the second phase (usually >6 months) is mainly of naïve CD4 cell reconstitution. As IRD invariably coincides with the primary phase of T memory cell redistribution, it has been postulated that this may be a memory T cell versus pathogen/antigen recognition event.
Mycobacterium xenopi infections have been, uncommonly, reported as IRD.4 Because co-existence of multiple opportunistic organisms in the respiratory tract of patients with advanced HIV disease is common,5 diagnosing non-M tuberculosis infections can be difficult; in our patient the isolation of M xenopi from BAL fluid and sputum specimens and the clinical features all fit the diagnostic criteria for non-M tuberculosis infections.6 The differential time scales for the resolution of the apical radiographic abnormalities (rapid diminution after 10 days of PCP therapy) and the radiographic abnormalities of the right middle lobe (14 months) are compatible with concurrent granulomatous P carinii pneumonia (GPCP) and M xenopi pneumonia (MXIP).
The granuloma, a localised inflammatory process, can form part of the host’s immune protection response to infections or part of an autoimmune disease process. Patients with AIDS have T cell deficiency and consequently have difficulty in mounting a granulomatous reaction to infections.7 Despite this, our patient mounted a hyper-accentuated response weeks after commencing HAART.
Bondoc et al8 reported GPCP in three non-HIV patients with malignancy who shared similarities with our patient. GPCP occurred 2 weeks to 2 months after stopping corticosteroids compared with 3–8 weeks after receiving ART in our patient. All had minimal symptoms, a comparable time scale of immune reconstitution, and P carinii was not detected in the BAL fluid. These two reports seem to support recent evidence that the main pathway for T cell recruitment during granuloma formation is from the systemically activated T cell pool.9 Corticosteroid therapy suppresses peripheral circulating lymphocytes and its discontinuation leads to a rebound of peripheral lymphocytes,10 a process akin to the phase of memory T cell redistribution following ART.
The simultaneous occurrences of GPCP and MXIP are perhaps less surprising when viewed in the context of T memory cell (therefore diverse memory clone) redistribution. Recent evidence has shown that the T cell repertoire of granulomas in response to a primary pathogen is diverse. Only 30–60% in a single granuloma are specific to the inducing antigen, and systemically activated T cells with no specificity to the granuloma also have access to it.9
Cytokine gene polymorphisms11 and an abnormal cytokine profile12 have been associated with HIV IRD. This, together with a recent report of granulomatous pulmonary disease occurring in a patient following cessation of tumour necrosis factor (TNF)-α antagonist treatment,13 implies that perturbation of the cytokine profile can trigger granulomatous inflammation.
Host and antigenic factors implicated in the pathogenesis of granulomatous lung diseases are also likely to influence the expression of GPCP; in addition, immune dysregulation (systemic T cell pool and cytokine perturbation) may also trigger granulomatous inflammation.
The authors thank Drs G Brook and M Murphy for their critical comments and suggestions.
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