P874: DECIPHERING PLASMA CELL HETEROGENEITY AND TUMOR MICROENVIRONMENT IN LIGHT-CHAIN AMYLOIDOSIS USING SINGLE CELL RNA-SEQUENCING - A. Srivastava; R. Kumari; S. Adhikari; P. Sergeev; J. J. Miettinen; M. H. Suvela; K. Flanagan; A. Slipicevic; N. N. Nupponen; F. Lehmann; C. Heckman (HemaSphere, 2022)