Alveolar immune mediators in HIV-related pneumonia. Different role of IL-2 and IL-1 in inducing lung damage.

In order to elucidate the role played by alveolar cytokines in the pathogenesis of HIV-related lung damage, levels of interleukin (IL) 1 beta, IL-2, IL-6, tumor necrosis factor (TNF)-alpha, and interferon (Ifn) were assessed on supernatant of bronchoalveolar lavage fluid from 30 consecutive HIV-1 seropositive (HIVAb+) patients with clinical and radiologic evidence of pneumonia, from 20 HIV- seronegative (HIVAb-) patients with pulmonary sarcoidosis, and from 10 HIVAb- healthy control subjects. Cytokine levels were expressed as picogram (IL-1, TNF), nanogram (IL-6), and international unit (IL-2, Ifn) per milligram of albumin per deciliter. Total and differential cell counts, cytofluorimetric enumeration of CD3+, CD3+/DR+, CD4+, CD8+, and CD8+/CD16+ cells, as well as microbiologic investigations for opportunistic agents were performed on lavage pellets. HIV-related pneumonia was characterized by higher mean alveolar level of IL-2 (12 +/- 5 IU), and by more elevated mean counts of T cells (109 +/- 16), activated T cells (60 +/- 12), and CD8+ cells (90 +/- 13)/microliters if compared with both active sarcoidosis and control subjects, where respective values of 0.2 +/- 0.1 and 0.3 +/- 0.2 IU IL-2/mgAlb/dl, of 52 +/- 11 and 7 +/- 2 T cells, of 20 +/- 5 and 1.2 +/- 0.3 activated T cells, and of 11 +/- 2 and 3 +/- 0.6 CD8+ cells per microliter were found. HIV-infected patients with opportunistic lung infections (OIs) showed the highest mean IL-2 level (21 +/- 4 IU), and higher counts of both CD8+ (117 +/- 20) and CD8+/CD16+ (36 +/- 7) cells per microliter if compared with patients without evidence of OIs (respectively, 62 +/- 13 CD8+ and 18 +/- 3 CD8+/CD16+ cells per microliter). By contrast, extremely high IL-1 levels (1,463 +/- 760 pg), and IL-2 levels similar to control subjects (3.4 +/- 1.2 IU), were found in the absence of OIs. Different mechanisms depending respectively on IL-2-mediated cytotoxic cell recruitment and activation, or IL-1-mediated tissue injury may account for HIV-related lung damage, depending on the presence or absence of opportunistic agents.