The novel arthritis-drug substance MCS-18 attenuates the antibody production in vivo.

UNLABELLED: Influence of the novel arthritis drug-substance MCS-18 on the antibody (Ab) production against tetanus toxoid (TT) and diphtheria toxoid (DT) antigens was tested in vivo. Possible involvement of MCS-18 in Toll-like receptor (TLR) signalling pathway was further considered. MATERIALS AND METHODS: Immunization of male CD1 mice was done with subcutaneous injection of TT emulsified in Freund's Complete (FCA) or Incomplete Adjuvant (FIA) and mixed diversly with MCS-18 and different test substances. To investigate the influence of TLR activation Pam3Cys and lipopolysaccharide (LPS) emulsified in FIA were tested in combinations with MCS-18. Antibody production was analysed in vivo by tetanus- or diphtheria-toxin neutralization test. RESULTS: Immunogenicity of TT was significantly enhanced if administered together with FCA or TLR agonists Pam3Cys or LPS emulsified in FIA. It was shown that MCS-18 attenuated strongly the production of anti-TT Ab if administered together with the Ab elicitor FCA or TLR agonists in various combinations. MCS-18 was also active via oral administration. DISCUSSION: These findings suggest that MCS-18 could be a potent, non-toxic antagonist or a down-regulator of TLR signalling pathway. Investigations on further models are needed to establish ifMCS-18 may influence particularly the production of RA-specific auto-antibodies, too.

COX-2 inhibitors can down-regulate in vivo antibody response against T-dependent antigens.

There are many studies demonstrating by different experimental models that non-steroidal antiinflammatory drugs (NSAIDs), also known as cyclooxygenase-2 (COX-2) inhibitors, can modulate immune response such as lymphoid cells differentiation and proliferation. There are experimental data which show that activated B cells can express mRNA COX-2, release prostaglandins (PGs) and produce immunoglobulins in PGs dependent manner. In this study, using different COX-2 inhibitors and applying personalized immunization scheme, we confirmed that it is possible to modulate in vivo antibody response against T cell dependent antigens, substantiating the importance of PGE2 and E prostanoid receptor (EP-R) in antibody generation. Our results point out the fact that we must be more careful when we apply vaccines containing T-cell dependent antigens, such as tetanus or diphteric anatoxin, to the patients under an intense antiinflammatory treatment.