The application discloses a preparation method of rabbit round small sac
transfer factor, comprising the following steps: 1) mixing water for injection with ground rabbit round small sac, and homogenizing the mixture by a
colloid mill to obtain a homogenate; 2) centrifuging the homogenate after
cell crushing, performing tangential flow
filtration on the harvested supernatant, and collecting the permeate; 3) performing tangential flow
filtration on the permeate by using filter membranes with different molecular weight
cut-off pore sizes in stages to obtain crude products of rabbit round small sac
transfer factor with required molecular weight ranges; 4) mixing at least one crude product with a certain molecular
weight range in step 3) to obtain a primary product of rabbit round small sac
transfer factor; and 5) adjusting the pH and the
osmotic pressure of the primary product of rabbit round small sac transfer factor after
virus removal, performing sterilization
filtration, and obtaining rabbit round small sac transfer factor. The application adopts the tangential flow filtration in stages, establishes precise and effective separation and concentration technology of rabbit round small sac transfer factor and
small molecule purification technology, and can prepare rabbit round small sac transfer factors with various molecular weight ranges according to different technological process flows by selecting filter membranes with different molecular weight
cut-off pore sizes.