INTRODUÇÃO: A doença pneumocócica invasiva (DPI) tem alta mortalidade sendo o pulmão órgão de intenso acometimento. Na DPI caracterizou-se localmente importante processo inflamatório agudo com expressivo aumento de macrófagos, polimorfonucleares e fenômenos exsudativos como edema e hemorragia intra-alveolar. Concretizou-se uma resposta inflamatória proeminente com redução dos fenômenos de apoptose que se traduziu por aumento significativo de citocinas pró-inflamatórias, exceto IL-6 e IL-8, aumento de Toll-2, ativação do complemento, aumento de expressão de ICAM- 1 e CD 14 que em conjunto favorecem o estabelecimento dos fenômenos inflamatórios. A diminuição significativa das células NK e das células de Langherhans, IL-6 e IL-8 reflete comprometimento da imunidade inata. Tal comprometimento poderia ser responsável pela diminuição dos linfócitos TCD4+ e TCD8+ com consequente baixa produção de IFN. Em resumo, as lesões teciduais graves na DPI seriam decorrentes do comprometimento parcial da imunidade inata, em especial das células NK e das células de Langherhans, do prejuízo da imunidade adaptativa e da redução da apoptose como possível estratégia defensiva do pneumococo

INTRODUCTION: Invasive pneumococcal disease (IPD) is a condition with high mortality rates, the lungs being intensely attacked. The in situ immune response was determined, in blocks recovered from 22 necropsies of adults who died from IPD in the lungs, by quantitative immune cell phenotype (CD57-NK, CD1a, CD68, antigen S-100, TCD4, TCD8, CD20), Complement-C3, ICAM-1, CD14, Caspase-3 and cytokine (interferon , TNF, TGF, interleukin - IL-1, IL-2, IL-4, IL-6, IL-8, IL- 10), Toll-2 and SP-A (surfactant). A locally important acute inflammation process was characterized in IPD, with significant rise in macrophages, neutrophils and exsudative phenomena such as edema and intra-alveolar hemorrhage. Compared with the lungs from age-matched controls, results from patients with IPD showed significant depletion of NK, CD1a,CD4+, CD8+, CD20+ cells, interferon , IL-4, IL- 6 , IL-8, TGF and Caspase-3 (apoptosis). On the other hand, S-100, Toll-2, IL-1, IL-2R, IL-10, ICAM-1, CD14 and SP-A were more frequently seen in the alveoli of patients with IPD than in controls. A pronounced inflammatory response was detected, with decrease in apoptosis phenomena that translated into significant increase of pro-inflammatory cytokines, except for IL-6 and IL-8, increase in Toll-2, complement activation, increased ICAM-1 and CD-14 expression, which altogether favored installation of the inflammatory processes. A significant decrease in NK and Langherhans cells, IL-6 and IL-8 reflect the harm to the innate immune system. This could respond for the decrease in TCD4+ and TCD8+ lymphocytes, with a consequent low IFNy output. Briefly, the severe tissue lesions in IPD could be a consequence of the partial damage to the innate immunity, particularly of NK and Langherhans cells, of adaptive immune dysfunction, and of apoptosis reduction possibly as a defense strategy of the pneumococcus