Autoimmune neurological diseases are often treated by immunoadsorption using a conventional plasma separator and tryptophan‐immobilized column (IA). However, there is only one case report on treatment with immunoadsorption using a selective plasma separator and tryptophan‐immobilized column (SeIA) in clinical practice. This study aimed to investigate the removal characteristics of antibodies against acetylcholine receptors (AChRAb), immunoglobulin G, fibrinogen, and factor XIII (FXIII) in IA and SeIA in four patients with myasthenia gravis. A total of 19 sessions of immunoadsorption were performed (five sessions of IA and 14 sessions of SeIA) when the processed plasma volume was 2 L. The corresponding reductions were 52.5% ± 6.2% for AChRAb, 58.8% ± 4.2% for fibrinogen, and 36.9% ± 5.5% for FXIII after one session of IA. The corresponding reductions were 45.2% ± 9.9% for AChRAb, 3.5% ± 6.9% for fibrinogen, and −4.6% ± 11.1% for FXIII after one session of SeIA. The removal rates for AChRAb, fibrinogen, and FXIII in IA were significantly higher than those in SeIA. IA could effectively remove AChRAb, and SeIA could retain fibrinogen and FXIII. IA can be combined with SeIA, resulting in both IgG autoantibodies removal by IA and retention of coagulation factors by SeIA.

Plasma volume (PV) variation during therapeutic apheresis (TA) (such as plasma exchange [PE] and selective PE using albumin solution as replacement solution or immunoadsorption plasmapheresis) has been considered to be unignorable. It changes the concentration of the target molecule and might impact its removal rate (RR.) This study aimed to evaluate the effects of PV variation on the calculation of the RR of fibrinogen and immunoglobulin by categorizing the hematocrit (Ht) change during TA into two patterns, that is, increased group and decreased group. In all modalities of TA, the Ht level frequently changed during apheresis sessions. In calculating RR, RR calculated with Ht adjustment was significantly higher than that calculated without adjustment in the increased group and significantly lower than it in the decreased group. Therefore, RR might have been underestimated in the increased group and overestimated in the decreased group when RR was calculated without Ht adjustment. Ht adjustment is suggested to be crucial in calculating RR in TA.

Low-density lipoprotein (LDL) apheresis is effective for nephrotic syndrome in drug-resistant focal segmental glomerulosclerosis (FSGS). Dextran sulfate adsorption of LDL (DSAL) is widely used for this purpose. The Liposorber LA-15 system performs DSAL by membrane plasma separation (mDSAL) using an MA-03 plasma purification device. However, sufficient blood flow (Qb) frequently cannot be obtained from a peripheral vein with mDSAL. The recommended plasma filtration flow rate (Qf) when using the OP-05W membrane plasma separator is no more than 1/3 of Qb, giving plasma removal efficiency (PRE) of about 30%. In contrast, the centrifugal blood component separator Spectra Optia has PRE of 87–92.5% because centrifugal separation enables effective separation of plasma components even at low Qb. Here, we present the case of a man in his 40s with FSGS, for whom we began treatment with mDSAL with the intention of completing a 12-session cycle, but extended treatment times were required due to low Qb. Therefore, we switched to DSAL by centrifugation (cDSAL) using the Liposorber LA-40 system from the 6th session onward. Treatment time decreased from 190 min for the fifth session using mDSAL to 140 min for the sixth session using cDSAL. Mean treatment time also decreased from 155 ± 9 min for mDSAL (5 sessions) to 119 ± 20 min for cDSAL (7 sessions). Moreover, the LDL removal rate at a processed plasma volume was similar for both modalities. In conclusion, cDSAL can enable efficient plasma separation even with low Qb, with a comparable LDL removal rate and shorter treatment time relative to mDSAL.

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