System Serology Examples

Dan's use-case:

• What’s being collected is “Antigen-specific FcR Binding” with results in units of median fluorescence intensity
• FcR is a cell surface receptor that binds to the Fc (constant domain) of an IgG antibody
• The antigens are HA’s from a variety of influenza strains
• Antigens are bound to magnetic micro beads
• Subject serum is added and antigens are bound by antibodies specific for them
• Microbeads with an antibody-antigen complex are separated from microbeads with unbound antigens
• Various FcR’s are added and incubated with the antibody-antigen microbead complexes
• The mdFI of the resulting antigen-antibody-FcR microbead complex is assessed

Since different IgG subclasses bind with different affinities to different FcR’s and different FcR’s trigger different effector responses, the results give an insight into the types of effector responses elicited towards each antigen. See, e.g., https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5333794/

There’s some difficulty in modeling this since there are basically two binding targets of the antibody – 1.) the antigen via the variable region of the antibody and 2.) The Fc receptor via the constant region of the antibody. A further subtlety is that constant regions of the antibodies can bind to multiple FcR’s, so it’s not like we can say we are measuring IgG1-antigen complex (ISTEST)  binding to the FcR (ISBDAGNT). Modeled this would also mean we’d either blow ISTESTCD terminology or need a work-around such that antibody-antigen complexes could be listed in the SUPPIS.