Table 1.

Similarities and differences between CAIA and CIA animal models. CFA: Complete Freund's adjuvant, RA: rheumatoid arthritis, CIA: Collagen-Induced Arthritis, and CAIA: Collagen Antibody-Induced Arthritis.

	CIA model	CAIA model
Induction method	Type II collagen/CFA	Monoclonal antibodies against type II collagen
Feature of arthritis	Polyarthritis	Polyarthritis
Similarities to human RA	(i) Activates adaptive immune system. (ii) Produces antibodies against specific epitopes on type II collagen in joints. (iii) Synovial inflammation due to infiltrating immune cells. (iv) Cartilage and bone destruction. (v) Increases RF and ACPA	(i) Antibodies against specific epitopes on type II collagen in joints. (ii) Synovial inflammation due to infiltrating immune cells. (iii) Cartilage and bone destruction.
Advantages	(i) Study CIA development in relation to the adaptive immune systems. (ii) Study immunity specific to cartilage. (iii) No sex-bias	(i) Induces arthritis in many mouse strains. (ii) Develops consistent arthritis severity and with almost 100% incidence. (iii) Effectively studies test articles in a short study period (1-2 weeks). (iv) RF and ACPA negative. (v) No sex-bias
Disadvantages	(i) Restricted to select mouse strains. (ii) Animal housing conditions can affect arthritis severities and incidences. (iii) A long study period due to the slow onset of arthritis (1-2 months). (iv) Strongly affected by CFA presence.	(i) Does not involve the full spectrum of immune activation. (ii) Animal housing conditions can affect arthritis severities and incidences.