providing a retainer with a plurality of {HEAD ~ compartments}, wherein a first compartment comprises a first antibody and a second compartment comprises {TAIL ~ a second antibody} 
providing a retainer with a plurality of { HEAD ~ compartments } , wherein a first compartment comprises a first antibody and a second compartment comprises { TAIL ~ a second antibody }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL