Table 2.

Selected antibodies used to study biosynthesis and maturation of mouse MHC class II molecules

Antibody	Reactivity	Isotype (murine unless indicated)	Specificity in immunoprecipitation	Reference (Original and application)
In-1	Ii	Rat IgG2b	Recognizes cytoplasmic epitope near N terminus of Ii. Immunoprecipitates free Ii and Ii/class II complexes. Recognizes denatured or non-denatured, full-length and C-terminally truncated Ii fragments, but not CLIP.	[23,59]
P4H5	Ii	Armenian Hamster	Recognizes residues 99–116 of Ii, a lumenal epitope immediately C-terminal of CLIP.	[60–62]
M5/114	I-A/I-E β I-A^b,d,q, I-E^d,k (Not reactive with I-A^k,s,f,g7)	Rat IgG2b	Recognizes β chain epitope (β1 domain = β chain binding groove domain). Competes with MK-D6, but no detectable preference for immature/mature class II.	[60,63,23,61]
Y3P	I-A^{b,f,p,q,r,s,u,v} weakly with I-A^k, also cross-reacts with all rat I-A-like molecules	IgG2a	Recognizes peptide binding domain of mature αβ dimers and αβ/Ii complexes.	[23,61,64]
10-2.16	I-A^k,r,f,s,g7 β but not reactive with I-A^b,d,p,q	Mouse IgG2b	Recognizes β1 domain.	[65,61,66,24]
K24-199	I-Aα, including I-A^d,k,g7	IgG2a	Does not recognize newly synthesized class II in presence or absence of Ii, prefers a more mature conformation.	[65,61,67]
MKD6	I-A^dβ (not reactive withI-A^k,b,s,f,a)	IgG2a	Recognizes extracellular β chain epitope (β1 domain, competes with M5/114). Prefers more mature (e.g., DM-edited) conformations of I-A^d (IP is poor at early time points, more efficient after ~1 hr chase, and more efficient from DM-expressing than DM-negative cells).	[60,65,68–69]
B21-2	I-A^b,d,g7 β	Rat IgG2b	Recognizes β chain of properly folded αβ dimers. No detectable preference for mature/immature/DM-edited class II.	[68,70]
14-4-4S	Common I-Eα chain (N.B. not all haplotypes express I-E.)	IgG2a	Recognizes α chain of properly folded αβ dimers.	[65,61,71–72]