MO299RELATIONSHIP BETWEEN LOW-TITER PHOSPHOLIPASE A2 RECEPTOR ANTIBODY AND TREATMENT RESPONSE OF IDIOPATHIC MEMBRANOUS NEPHROPATHY

Abstract

Abstract Background and Aims The circulating anti-Phospholipase A2 receptor (PLA2R) antibody has been widely detected since its discovery in 2009. It was suggested that the cut-off of serum PLA2R antibody (PLA2RsAb) should be reset at below 20 RU/mL to prove diagnostic efficacy. The correlation between low titer PLA2RsAb and treatment response has not been discussed. In this study, we focused on the low titer PLA2RsAb during follow-up of PLA2R-related IMN. Method We retrospectively enrolled 43 Chinese patients with biopsy-proved PLA2R-related IMN from March 2017 to October 2019. Baseline data were collected including age, gender, serum creatinine (Scr), albumin (Alb), 24h urine protein (24hUP), and PLA2RsAb at biopsy. PLA2RsAb was detected at one month, three months, six months and one year. The patients were stratified into three groups by the lowest PLA2RsAb titer during follow up. Low titer group was defined as anti-PLA2R antibody ＜2RU/mL (53.5%, n=23). Median titer group was defined as anti-PLA2R antibody >2 but ＜20RU/mL (32.6%, n=14). High titer group was defined as anti-PLA2R antibody >20RU/mL (13.9%, n=6). Complete remission (CR) was defined as 24hUP ＜0.3g/d. Partial remission (PR) was defined as 24hUP at the range of 0.3-3.5g/d and a reduction >50% of the baseline proteinuria. No remission (NR) was defined as absence of CR or PR at one-year. Results In the entire cohort, patients were 49 ± 16 years old with 28/15 male/female ratio. Baseline data of low, mid and high titer group were as follows: the median PLA2RsAb were 34.3(22.1, 314), 103(55.8, 361), 73.6(53.0, 215)RU/mL, P = 0.305; the median 24hUP were 6.8(3.5, 12.4), 6.4(5.6, 8.9), 4.9(3.4, 7.2)g/d, P = 0.493; the average Scr were 100.4 ± 60.0, 92.3 ± 29.2, 82.0 ± 21.9 umol/L, P = 0.681; the median Alb were 27.0 ± 5.7, 23.8 ± 5.8, 30.2 ± 3.3 g/L, P = 0.054. The rate of CR, PR, NR were 34.8% (8/23), 34.8% (8/23), 30.4% (7/23) in low titer group, 7.1% (1/14), 71.4% (10/14), 21.4% (3/14) in mid titer group, 0% (0/6), 66.7% (4/6), 33.3% (2/6) in high titer group, P = 0.119 Conclusion The correlation between low titer PLA2RsAb and treatment response showed no statistical significance.