Efecto in vitro de la tuftsina (L-prolil-L-arginina) en la capacidad oxidativa de los polimorfonucleares en niños recién nacidos pequeños para su edad gestacional / Tuftsin (L-prolil-L-arginina) has the function of activating cellular macrophages and polymorphonucleras in newborns

Se comunican los resultados de un trabajo realizado para determinar el efecto de la tuftsina sintética en la capacidad oxidativa de células polimorfonucleares de niños recién nacidos pequeños para su edad gestacional, ya que se ha demostrado que está disminuida la actividad fagocítica de macrófagos y polimorfonucleares (PMNs) comparada con las células de niños con peso adecuado para su edad gestacional. En los resultados se observó un efecto de estimulación de la capacidad oxidativa de los PMNs con tuftsina sintética a través de incrementar la reducción de nitroazul de tetrazolio, lo que sugiere que la baja capacidad oxidativa de las células de recién nacidos pequeños para su edad gestacional no se relaciona con un defecto intrínseco celular

Comparison of group B streptococcal hyperimmune globulin and standard intravenously administered immune globulin in neonates.

Standard intravenously administered immune globulin (IVIG) contains varying amounts of group B streptococcus (GBS) antibody. A GBS hyperimmune IVIG was produced by immunizing plasma donors. The GBS type-specific opsonic activity was > or = 90% in the hyperimmune IVIG at a 1280 dilution-1 versus at a 10 dilution-1 in standard IVIG. Suckling rat survival after GBS type-specific infection was 100% when the rats were treated with hyperimmune IVIG versus < or = 20% with standard IVIG. To evaluate the effect of this product on GBS antibody levels and clinical toxic effects, we randomly administered either GBS hyperimmune IVIG, 500, 250, or 100 mg/kg, or standard IVIG, 500 mg/kg, to 20 neonates with suspected sepsis. No adverse effects were observed. Total and subclass serum IgG levels reflected only the dose; serum GBS type-specific IgG and opsonic activity reflected both the product and dose of IVIG administered. Standard IVIG did not significantly increase serum GBS type-specific IgG, whereas hyperimmune IVIG, 500 mg/kg, produced a fourfold rise for > 6 weeks; more variable increases were observed after 250 and 100 mg/kg doses were given. Serum GBS type-specific opsonic activity correlated with serum GBS type-specific IgG levels (R2 = 0.74; p < 0.0001). Further studies of this or similar products will be necessary to determine whether GBS type-specific antibody improves the outcome of GBS-infected neonates.

Técnicas para evaluar la capacidad fagocítica, opsonica y bactericida del leucocito polimorfonuclear / Techniques to evaluate the phagocytic, opsonizing and bactericidal ability f the polymorphonuclear leukocyte

Para estudiar la función in vitro del leucocito PMN se estandarizaron las técnicas inmunológicas de capacidad fagocítica, opsónica y bactericida. La capacidad fagocítica se midió en sangre total, incubando leucocitos del sujeto en estudios en presencia de su propio plasma con estafilococos aureus muertos y la actividad opsónica se determinó incubando células de un individuo sano con plasma del sujeto en estudio. Los frotis teñidos se leyeron al microscopio de luz, y los resultados se expresaron como índice fagocítico, esto es número de bacterias ingeridas por 100 PMN. La capacidad bactericida se estudió, incubando una suspensión de leucocitos con bacterias (E. coli) en rotación continua a 37-C, basada en la técnica de Quie y cols. Se tomaron alícuotas para recuento de colonias por dilución en placa a los tiempos 0,20, 60 y 120 minutos. Los resultados se expresaron como índice bactericida, esto es, número de bacterias vivas a los 120 minutos/número de bacterias vivas a los 20 min. Para optimizar las técnicas se analizaron los siguientes parámetros: número de leucocitos/ml de sangre o suspensión, concentración y cepa de referencia de E. coli/ml de suspensión, período de incubación, reproducibilidad de la técnica, variabilidad intraindividual e interindividual y en el tiempo. Una vez estandarizados dichos parámetros, los índices de capacidad fagocítica y opsónica fueron de 9.2 ñ 0.85 y 8.1 ñ 0.6 (x ñ ESM), respectivamente. El índice promedio de la actividad bactericida fue de 0.14 ñ 0.05. Las pruebas fueron discriminatorias en pacientes con sospecha clínica de alteración de la capacidad funcional del leucocito

Protective efficacy of a modified immune serum globulin in experimental group B streptococcal infection.

In spite of aggressive antimicrobial therapy and extensive support measures, the mortality rate in early-onset group B streptococcal infection continues to be exceedingly high. In previous studies, we have demonstrated that passive immunotherapy with fresh whole blood containing opsonic antibody-improved survival in human neonates with group B disease. Transfusion of whole blood, plasma, or other blood products has a number of drawbacks, however. In the present study, we have evaluated immune serum globulin and a preparation of ISG modified for intravenous use for levels of type-specific antibody, opsonic activity, and protective efficacy against type Ia, II, and III group B streptococci. Type-specific antibody was detected in most of the preparations tested. In general, the level in MISG was less than that in the comparison ISG lot. Opsonic activity was also detected in these preparations against the more antibody-sensitive group B strains but was not present for opsonin resistant strains of type Ia, II, and III. Both ISG and MISG provided protection in neonatal rats infected with group B streptococci; in most cases MISG was more efficacious than the ISG from which it was made. These studies suggest that passive immunotherapy with MISG may be a valuable adjunct to current regimens used in the management of early-onset group B disease. This would be especially so if donors could be selected whose serum or plasma contained high levels of opsonic and protective activity against both antibody-sensitive and antibody-resistant group B strains.

Interaction of E. coli strains with human serum: lack of relationship to K1 antigen.

Twenty-eight strains of E. coli isolated from infants were compared with respect to opsonic requirements, sensitivity to serum, and ability to activate serum chemotactic factors. Six of the strains were isolated from stools of healthy newborn infants; 22 were isolated from the cerebrospinal fluid or blood of infants with meningitis and/or septicemia. Eighteen of the strains had K1 polysaccharide antigen. Fourteen of the strains (seven with K1 antigen) activated complement via the alternative pathway and all of these strains were well opsonized in 4% pooled human serum. A higher concentration of serum was necessary to opsonize 12 of the 14 strains that did not activate the alternative pathway. A wide variation was also found in opsonic requirements of E. coli strains isolated from healthy and sick infants. There was no relationship of the K1 antigen to opsonic requirements, to capacity to activate complement via the alternative pathway, to generation of chemotactic factors, or to sensitivity to serum cidal activity. Therefore, the association of E. coli with K1 antigen and neonatal meningitis did not appear to be related to these bacteria-serum interactions.