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Int J Lepr Other Mycobact Dis ; 54(2): 294-9, 1986 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-3014027


Factors influencing the phagocytosis of mycobacteria by 33B rat Schwannoma cells and rat peritoneal macrophages were studied. Uptake of 14C-acetate-labeled Mycobacterium w by these cells was used to set up a radiometric phagocytosis assay. Incubation at 4 degrees C and treatment with sodium azide (0.2% to 1%), colchicine (10(-7) to 10(-3) M), cytochalasin B (0.2 micrograms/ml to 25 micrograms/ml), and dibutyryl cyclic AMP (10(-7) to 10(-3) M) inhibited the phagocytosis by both cell types in a similar manner. These experiments demonstrate similarities in the mechanism of phagocytosis of mycobacteria by Schwann cells and macrophages.

Macrófagos/fisiologia , Mycobacterium/fisiologia , Fagocitose , Células de Schwann/fisiologia , Animais , Azidas/farmacologia , Bucladesina/farmacologia , Células Cultivadas , Colchicina/farmacologia , Temperatura Baixa , Citocalasina B/farmacologia , Neurilemoma , Fagocitose/efeitos dos fármacos , Ratos , Azida Sódica
Parasite Immunol ; 8(2): 129-38, 1986 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-3517765


Abnormal phagocytosis of Mycobacterium leprae by macrophages of lepromatous patients was demonstrated under various conditions. The largest proportion of macrophages with an excessive bacterial load belonged to the lepromatous group of patients. Lepromatous macrophages treated with Cytochalasin B, an inhibitor of phagocytosis, exhibited a significantly lower degree of ingestion of heat-killed organisms whereas uptake of 'viable' organisms was not affected to the same extent. Regulation of phagocytosis was studied by noting the rate of phagocytosis of M. leprae after the ingestion of a primary particle viz carbonyl iron. Solely in lepromatous macrophages, phagocytosis of carbonyl iron did not result in a decreased uptake of M. leprae implying aberrant phagocytic activity. Lastly, excessive phagocytosis was always noted in macrophages of familial contacts of leprosy patients who displayed decreased Fc receptor expression after M. leprae ingestion. This is of interest since phagocytosis, like Fc receptor expression, is a membrane dependent event and other membrane associated defects have been recognized by us earlier in lepromatous macrophages.

Hanseníase/imunologia , Macrófagos/imunologia , Mycobacterium leprae/imunologia , Compostos Organometálicos , Antígenos de Bactérias/imunologia , Membrana Celular/fisiologia , Citocalasina B/farmacologia , Humanos , Ferro/farmacologia , Compostos Carbonílicos de Ferro , Macrófagos/ultraestrutura , Fagocitose/efeitos dos fármacos , Receptores Fc/imunologia , Tuberculose/imunologia
Infect Immun ; 41(1): 121-7, 1983 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-6345387


Macrophage cultures pulsed with viable Mycobacterium leprae were assessed for erythrocyte rosetting in three groups of individuals, i.e., normal subjects, and tuberculoid and lepromatous patients. Of these, only the lepromatous group showed a reduction in rosetting ability after infection with M. leprae. The specificity of such a reduction pattern was confirmed by using various mycobacteria to infect the macrophages. A threshold effect was noted in all three groups. Although a reduction was obtained in the amount of rosetting of macrophages from lepromatous patients with 10(4) acid-fast bacilli per culture, tuberculoid and normal macrophages resisted such an effect with as large a dose as 20 X 10(6) to 30 X 10(6) and 30 X 10(6) bacilli per culture, respectively. The M. leprae-caused alterations in macrophages from lepromatous patients were reversible by treatment with trypsin and colchicine. Cytochalasin B and Tween 80 were unable to alter the pattern. Treatment of cells with neuraminidase was inconclusive since it enhanced rosetting values of both control and infected cultures. These manipulations were significant in elucidating the target point of the host (macrophage) and parasite (M. leprae) interaction and in delineation of the external and internal effects upon the macrophages. Both M. leprae and macrophages were participants in Fc reduction, as treatment of the former with rifampicin and of the latter with cyclocheximide significantly augmented the rosetting ability. In conclusion, it appears that M. leprae, upon entering a lepromatous macrophage, initiates the production of a protein which acts via the microtubules to alter membrane topography. It is possible that the altered membrane prevents effective macrophage-lymphocyte interaction. This could be one of the mechanisms by which cell-mediated immunity is suppressed in lepromatous leprosy.

Hanseníase/imunologia , Macrófagos/imunologia , Mycobacterium leprae/fisiologia , Animais , Células Cultivadas , Colchicina/farmacologia , Cicloeximida/farmacologia , Citocalasina B/farmacologia , Humanos , Macrófagos/microbiologia , Neuraminidase/farmacologia , Polissorbatos/farmacologia , Receptores Fc/fisiologia , Rifampina/farmacologia , Formação de Roseta , Tripsina/farmacologia