<prompt> Which of the following is most useful in Rx of Kostmanns Syndrome ?SargramostimAldesleukinOprelvekinFilgrastim  <response>: Kostmann disease was first described in 1956 as an autosomal recessive disorder characterized by severe neutropenia and onset of severe bacterial infections early in life Filgrastimlenograstim G-CSF in Kostman syndrome There is an induction phase with G-CSF to evaluate the response of individuals, with an increase in absolute neutrophil count ANC 1500mL and clinical improvement after 10-15 days. The initial daily dose is 5 mgkg subcutaneously. If there is no response after 15 days, the daily dose is increased by 5 mgkg. If the response is rapid or excessive ANC 5000 mL, the dose is halved. Once the minimal daily dose is determined, the maintenance phase can begin, with monitoring of neutrophil counts every 3-6 months. Almost two thirds of patients respond to a daily dose of 2-10 ugkg, while 20 respond to 10-20 mgkg. A small percentage of patients require higher doses, up to 100 mgkg. Around 10 of patients are unresponsive to G-CSF therapy. Ref - harrison 20th edition 740 , medscape.com 