Maria J. Arroz

Intracellular activity of clinical concentrations of phenothiazines including thioridiazine against phagocytosed Staphylococcus aureus

The effect of thioridazine (TZ) was studied on the killing activity of human peripheral blood monocyte derived macrophages (HPBMDM) and of human macrophage cell line THP-1 at extracellular concentrations below those achievable clinically. These macrophages have nominal killing activity against bacteria and therefore, would not influence any activity that the compounds may have against intracellular localised Staphylococcus aureus. The results indicated that whereas TZ has an in vitro minimum inhibitory concentration (MIC) against the strains of S. aureus of 18, 0.1 mg/l of TZ in the medium completely inhibits the growth of S. aureus that has been phagocytosed by macrophages. The latter concentration was non-toxic to macrophages, did not cause cellular expression of activation marker CD69 nor induction of CD3+ T cell production of IFN-gamma, but blocked cellular proliferation and down-regulated the production of T cell-derived cytokines (IFN-gamma, IL-5). These results suggest that TZ induces intracellular bactericidal activities independent of the capacity to generate Type 1 responses against S. aureus.

Respostas das citocinas T 2 desencadeadas por Mycobacterium tuberculosis virulento nos doentes com tuberculose pulmonar em estado avançado

In vitro Type 1 and Type 2 cytokine responses were assessed in healthy Portuguese donors who were BGC vaccinated at birth and Mantoux positive (induration 5 ≥ mm) and pulmonary tuberculosis patients (TB). We evaluated the production of IFN-γ and IL-5, after PBMC from donors were stimulated with live M. tuberculosis H37Rv and the soluble antigen PPD, by standard ELISA techniques. These studies were extended to confirm intracellular presence of IFN-γ and IL-4 in specific T cell subsets by multi-parameter flow cytometry. PBMC from tuberculosis patients demonstrated significantly reduced amounts of IFN-γ when stimulated with PPD and M. tuberculosis, with no increase in IL-5 production towards all the antigens, when compared to the control group. Intracellular staining for IFN-γ in tuberculosis patients showed reduced frequencies of CD4 + and CD8 + T cell intracellular IFN-γ in comparison to healthy subjects. Tuberculosis patients demonstrated a mean increase of intracellular IL-4 after PBMC were stimulated with M. tuberculosis in the CD4 + phenotype, but more notably in the CD8 + subset. The increased secretion of IL-4 in tuberculosis patients was primarily in individuals with an advanced clinical form of the disease. Interestingly the findings using flow cytometry techniques somewhat contradicts the results obtained by ELISA. Intracellular IL-4 secretion is therefore a more sensitive measure of Type 2 cytokine production than quantitation of IL-5 by ELISA. These results suggest that a type 1 switch to a type 2 can occur, in patients with tuberculosis in an advanced stage. REV PORT PNEUMOL 2001; VII (2):

Respostas Th1 e Th2 desencadeadas por Mycobacterium tuberculosis virulento em doentes com tuberculose pulmonar

RESUMO Analisaram-se as respostas Th1 e Th2 desencadeadas por Mycobacterium tuberculosis virulento em doentes com tuberculose pulmonar (TP) e em dadores saudaveis vacinados pela BCG. Efectuaramse comparacoes entre a capacidade que as celulas T apresentavam para proliferar e para produzir IFN-γ e IL-5 em resposta aos derivados de proteins purificada (PPD), M. tuberculosis H37Rv (Mtb), e M. tuberculosis H37Rv inactivado pelo calor (hk Mtb). Este estudo demoostrou que os individuos sauda-vels vacinados com BCG evidenciaram um maximo de proliferacao e producao de IFN-γ em resposta ao painel de antigenios, e que Mtb vivo destencadeou uma resposta significativamente mais forte que a obtida pelo Mtb inactivado pelo calor. Embora os doentes com tuberculose pulmonary mostrassem respostas medias mais baxies de proliferacao e producao de IFN-γ cm relacao aos eontrolos saudaveis, a resposta proliferativa ao PPD nao foi significativamente reduzida, enquanto que a resposta ao Mtb e hk Mtb foram, significativas estatisticamitante. Em conclusao na tuberculose pulmonar a producao de IFN-γ pode estar reduzida sem um concomitante aumento de IL-5, confirmandose assim nao existir uma mudanca de resposta Th1 para Th2 na tuberculose pulmonar. REV PORT PNEUMOL 1998; IV (4):393-402