The presence of HLA-DR B1 shared motif does not influence cyclophosphamide and methotrexate cytotoxicity in rheumatoid arthritis patients.

In the present study we investigated the relation between cyclophosphamide and methotrexate toxicity and the presence of HLA- DR B1 alleles in rheumatoid arthritis patients. Seventy-eight such patients (67 women and 11 men) were observed for 12 months. Eighteen were treated with intravenous cyclophosphamide, 28 with oral methotrexate, and 32 with intramuscular gold salts. The prevalence of this shared motif was higher in the study population than in the healthy controls. However, detailed observations did not demonstrate a relation between particular genotype and drug intolerance. Based on the obtained findings we concluded that HLA-DR B1 typing cannot affect cyclophosphamide or methotrexate tolerance in rheumatoid arthritis patients. However, taking into account the relatively small number of patients expressing single genotype, further studies are recommended.