Table 1.

HLA characteristics of antibody and antigen that might affect clinical outcomes

	Comment	Reference
HLA antibody
Concentration	Not currently possible to measure antigen-specific concentration of antibody (see Figure 3)
Antibody binding to HLA in solid phase assay (readout a combination of avidity and concentration)	Measureable by microbead assays	[2, 4]
Class	Mostly IgG, early reports of IgM mediated AMR and occurrence of IgA	[20, 21]
Subclass	Early studies show heterogeneity in responses	[21, 22]
Affinity	Measurement under investigation
Glycosylation	Measurement under investigation
Cellular binding	CDC and FC crossmatches Endothelial binding	[2, 23]
Inhibitors
Soluble HLA	Early reports of methods to quantify
HLA-E	Early reports of correlation with clinical outcomes	[24]
Idiotypic antibodies	Hard to measure with current tools but could be important	[25]
Immune complexes
HLA-sHLA immune complexes	Not currently measureable