Sheep red blood cells coated with rabbit anti-sheep erythrocyte antiserum (hemolysin) have traditionally been used to assay the activity of the complement classical pathway in serum samples. These assays yield the CH50 titer of the serum (Morgan, B.P. (2000); Dodds, A.W. and Sim, R.B. (1997)).
EA are supplied at assay-ready concentrations in the traditional buffer used in CH50 assays (GVB++). They are prepared fresh every Monday morning and need to be ordered by Friday in order to receive them the next week. They are shipped Monday afternoon by overnight courier for delivery on Tuesday (or Wednesday for most international shipments). They can usually be used for 2 weeks after preparation. They are shipped cold, but are not harmed by extended periods at room temperature (note that they circulate 60-90 days a 37oC in vivo). They should be washed once before each use (3 min at 500 to 1000 x g at 4oC) and resuspended at the original concentration in GVB++ to reduce background. This procedure may also be used to concentrate the cells. This may be accomplished by reducing the volume used to resuspend the cells.
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