[Effect of cyclophosphamide in experimental histoplasmosis in the rat]. / Acción de la ciclofosfamida en la histoplasmosis experimental de la rata.

Histoplasmosis is a fungal disease caused by the dimorphous fungus Histoplasma capsulatum (Hc). Cyclophosphamide (Cy) was used as an immunomodulator capable of modifying the course of the disease, as well as of regulating the mechanisms involved in T-lymphocyte mediated immune response. Rats were subjected to intracardiac inoculation of Hc followed by a fractionated treatment with a 100 mg/kg body weight dose of Cy on days +4, +5, +6, +7 and +11 pi. Until day 26 pi, treatment with Cy caused 85% mortality whereas no mortality was observed among animals only inoculated with Hc. On day 14 pi, the group of Hc animals showed a delayed hypersensitivity test (DH) of 26.60 + 13.96 as determined by the swelling of the leg. Conversely, DH was significantly depressed in rats inoculated with Hc and treated with Cy: 3.88 +/- 1.00 (p < 0.01). Colony forming units count in this group was 2020 CFU/g of spleen, and 24 CFU/g of spleen (p < 0.01) in controls. A macroscopic study of the organs revealed that the animals in the Hc+Cy group had spleenomegaly and lungs with granuloma and hemorrhagic spots. The controls only presented small lung abscesses. These findings lead to the conclusion that Cy causes a deterioration of cell mediated immune response which results in the manifestation of an acute, fatal experimental mycosis.

Cyclophosphamide effect on Paracoccidioidomycosis in the rat

La paracoccidioidomicosis es una enfermedad endemica fungica ampliamente distribuida en Latino-America. La ciclofosfamida ha sido usada como potente imunosupresor para modular la respuesta inmune, en um modelo experimental infectado con Paracocidioides brasiliensis. Ratas macho buffalo/sim endocriadas de 250-300 gr. de peso, fueron inoculadas por via intracardiaca con 5.10 elevado a sexta potencia celalas de P. brasiliensis en fase levaduriforme...

Cyclophosphamide effect on paracoccidioidomycosis in the rat.

Paracoccidioidomycosis is an endemic fungal disease widely distributed throughout Latin America. The potent immunosuppressor cyclophosphamide (CY) has been used to modulate host immune response to Paracoccidioides brasiliensis in an experimental model. Inbred male Buffalo/Sim rats weighing 250-300 g were inoculated with 5 x 10(6) P. brasiliensis cells of the yeast phase form by intracardiac route. One group of animals was treated with 20 mg/kg body weight at days +4, +5, +6, +7, +11 and +12 post-infection (pi.), while a control group was infected alone. No mortality was recorded in either group. Treated rats presented: a) a decrease in granuloma size, which contained less fungal cells; b) a lack of specific antibodies up to 35 days pi., and c) a significant increase in the footpad swelling test (DTH) against paracoccidioidin. Splenic cell transfer from CY-treated P. brasiliensis-infected donors to recipients infected alone led to a significant increase in DTH response in the latter versus untreated infected controls. Likewise, in treated infected recipients transferred with untreated infected donor spleen cells, footpad swelling proved greater than in controls. Thus, it would seem that each successive suppressor T lymphocyte subset belonging to the respective cascade may be sensitive to repeated CY doses administered up to 12 days pi.. Alternatively, such CY schedule may induce the appearance of a T cell population capable of amplifying DTH response.