Doshi J B, Ravetkar S D, Ghole V S, Rehani K
Serum Institute Research Foundation, 212/2, Hadapsar, -411028, Pune, India.
Biologicals. 2003 Sep;31(3):187-9. doi: 10.1016/s1045-1056(03)00038-1.
DPT, a combination vaccine against diphtheria, tetanus and pertussis is available since many years and still continued in the national immunisation schedule of many countries. Although highly potent, reactions to DPT vaccine are well known, mainly attributed to the factors like Pertussis component, aluminum adjuvant and lower purity of tetanus and diphtheria toxoids. The latter most important aspect has become a matter of concern, specially for the preparation of next generation combination vaccines with more number of antigens in combination with DPT. Purity of toxoid is expressed as Lf (Limes flocculation) per mg of protein nitrogen. The Kjeldahl method (KM) of protein nitrogen estimation suggested by WHO and British Pharmacopoeia is time consuming and less specific. Need has been felt to explore an alternative method which is quick and more specific for toxoid protein determination. DC (detergent compatible) protein assay, an improved Lowry's method, has been found to be much more advantageous than Kjeldahl method.
白喉、破伤风和百日咳联合疫苗（DPT）多年来一直可用，并且仍在许多国家的国家免疫规划中继续使用。尽管DPT疫苗效力很高，但对其的反应是众所周知的，主要归因于百日咳成分、铝佐剂以及破伤风和白喉类毒素纯度较低等因素。后一个最重要的方面已成为一个令人担忧的问题，特别是对于制备含有更多抗原与DPT联合的下一代联合疫苗而言。类毒素的纯度以每毫克蛋白质氮的Lf（絮状单位）表示。世界卫生组织和英国药典建议的凯氏定氮法（KM）测定蛋白质氮耗时且特异性较差。人们感到需要探索一种替代方法，该方法对于类毒素蛋白质的测定快速且更具特异性。去污剂兼容（DC）蛋白质测定法是一种改进的洛瑞法，已发现它比凯氏定氮法更具优势。
