Comparative study of lymphocyte-suppressive potency between prednisolone and methylprednisolone in rheumatoid arthritis

We compared lymphocyte-suppressive potencies of prednisolone and methylprednisolone in rheumatoid arthritis (RA). IC₅₀s of the glucocorticoids (GCs) on concanavalin A-induced blastogenesis of peripheral-blood mononuclear cells (PBMCs) from 44 RA patients and 30 healthy subjects were estimated in vitro, and differences in the IC₅₀s of the two GCs were evaluated. The mean (±SD) IC₅₀s for prednisolone and methylprednisolone on PBMC-blastogenesis of RA were 17.2±17.1 and 12.6±18.4 ng/ml, respectively, and no significant differences were observed between prednisolone-IC₅₀ and methylprednisolone-IC₅₀. In contrast, the mean IC₅₀s of prednisolone and methylprednisolone on healthy PBMCs were 19.4±22.4 and 3.7±3.9 ng/ml, respectively, and thus methylprednisolone potency was significantly higher than prednisolone potency (p<0.01). Methylprednisolone potency against PBMCs in RA patients exhibiting a high level of rheumatoid factor (RF) (>20 IU/ml) and the rheumatoid arthritis particle-agglutination value (RAPA) (>80) was significantly higher than that of patients exhibiting a lower level of RF or RAPA (p<0.05). In prednisolone-IC₅₀, however, such differences between the two patient-subgroups were not observed. Unlike reported cases of renal transplantation and healthy subjects, there was no difference in the lymphocyte-suppressive potencies for both prednisolone and methylprednisolone on RA-PBMCs. However, PBMCs from RA patients exhibiting high levels of RF or RAPA are more sensitive to methylprednisolone rather than prednisolone.