Using Akaike's method of multivariate autoregressive modeling (AR), we analyzed the fluctuation of the CD4 and CD8 lymphocyte subsets in the peripheral blood and the plasma level of immunoglobulin G (IgG) in two control healthy subjects, one systemic lupus erythematosus (SLE) patient and two rheumatoid arthritis (RA) patients, and three hemodialysis (HD) patients. Akaike's relative power contribution (ARPC) and impulse response curves were found to be useful to demostrate the features of malfunction of T lymphocytes in the IgG regulation in each pathologic state: the instability of the IgG regulating system in SLE, the delayed responses of IgG regulation in RA and HD patients.
