Citocina. ¿La terapéutica del futuro? / Citokines. The therapy in the future?

Se definen qué son las citocinas y se describe el papel de la interleucina-1 como un ejemplo de las fuciones que desempeñan. Actualmente se han encontrado más de 40 citocinas que se han agrupado en 1) factores de crecimiento, 2) interleucinas, 3) interferones, 4) quimiocinas y 5) otras. Hoy en día, mediante transfección genética, se han preparado 11 citocinas para aplicación terapéutica; de éstas, la eritropoyetina, el factor estimulante de colonias granulocito-monocito y el factor estimulante de colonias granulocito-monocito y el factor estimulante de colonias de granulocitos se utilizan con buen éxito para estimular la producción de glóbulos rojos, granulocitos y de monocitos en algunas patologías con daño a la médula ósea. Después de varios años de aplicación clínica, el uso de los interferones alfa, beta y gamma se han visto limitados a infecciones como la hepatitis B o C y algunos tipos de cáncer como la leucemia de células peludas y la leucemia granolocítica crónica. Las otras citocinas, como las interleucinas 2, 3, 4, 6 y el factor estimulante de colonias de monocitos, empiezan a mostrar su utilidad terapéutica en algunos ensayos clínicos. Se espera que en el futuro algunas de ellas, solas o combinadas con otras u otros activadores inmunológicos curen enfermedades como el síndrome de inmunodeficiencia adquirida o el cáncer

Differential responses of CD34-positive acute myelogenous leukemic blasts to the costimulating effects of stem cell factor with GM-CSF and/or IL-3

Stem cell factor (SCF), a c-kit ligand, has a preferential effect on the proliferation of several classes of immature hematopoietic progenitor cells in combination with GM-CSF or IL-3. To analyze the costimulatory role of SCF in leukemic growth, we investigated the effect of SCF in the presence of GM-CSF and/or IL-3 on isolated CD34-positive (CD34+) leukemic blasts from 15 patients with acute myelogenous leukemia (AML). Cultures of CD34+ cells from normal bone marrow were used as controls. When the proliferation of CD34+ AML blasts in the presence of GM-CSF and/or IL-3 were evaluated in vitro for the effects of SCF, two patterns emerged. In one pattern, CD34+ AML blasts responded with a significant increase in DNA synthesis and/or colony formation when SCF was used with GM-CSF and/or IL-3 relative to the growth with SCF alone; This result is consistent with those CD34+ bone marrow cells from normal donors. Six patients (40%) were included in this category. The addition of SCF as a single factor resulted in colony formation in all six of these cases. In the other pattern, nine of the patients (60%) had CD34+ leukemic cells whose growth with SCF plus either GM-CSF, IL-3, or GM-CSF+IL-3, was not significantly different from the growth noted in the presence of SCF alone. Among them seven cases that did not form colonies in response to SCF alone, and one case showing autocrine, background growth were included. In the six cases in which the costimulating effects of SCF were documented, CD34+ c-kit+ blasts comprised 50.5 +/- 18.7% of the CD34+ leukemic blasts-higher than 21.8 +/- 19.4% of cases in which the costimulating effect of SCF was not documented. In the cases showing high c-kit antigen expression(> or = 40%), SCF had a costimulatory effect in 71% (5/7) of the patients. In conclusion, our data indicate that CD34+ leukemic blasts from a good proportion of patients with AML did not respond to the costimulating effects of SCF in the presence of GM-CSF adn/or IL-3, in contrast to those CD34+ bone marrow cells from normal donors. The possible use of SCF for acute leukemia must await further cytogenetic and molecular studies, which should clarify the preferential costimulating role of SCF in normal hematopoiesis.

Effect of IL-3 and E. coli LPS on the proliferation of mouse bone marrow cells in vitro

Bone marrow cells from adult BALB/c mice were cultured at 37-C, with 5% CO2 in air, in RPMI 1640 medium complemented with fetal serum. The addition of IL-3 (5% of WEHI-3-conditioned medium) or E. coli lipopolysaccharides (LPS, 50 µg/ml) to the cultures stimulated cell proliferation (1.29 and 1.22-fold, respectively, relative to control culture), whereas the simultaneous addition of the two factors reduced the number of cells recovered by 38% relative those from control cultures (which were around 2.83 x 10***5 cells for each 10***6 plated cells). The frequency of blasts and cells with surface Ig presented the same pattern of variation (o.07 and 0.02%, respectively, in control cultures). The inhibitory effect of IL-3+LPS on cell proliferation was evident from the first day of culture, but more apparent on day 3. Macrophage-colony stimulating factor (M-CSF, L929-conditioned medium) and LPS each given alone stimulated proliferation but reduced it when given together. In contrast, fetal liver cells were not affected by the simultaneous addition of IL-3 and LPS or by M-CSF and LPS. The mechanism of action of the cumulative effect of these two factors in unknown. Since crude cell-conditioned medium was used as the source of IL-3, it is possible that another factor present in this medium interacts with LPS to cause the inhibitory effect on cell proliferation