scRNAseq also predicted upregulated T-cell/B-cell interactions due to a B-cell MHCII-related gene enrichment in Apoe–/– mice aorta adventitia in a model of hyperhomocysteinemia-accelerated atherosclerosis.68 Mechanistically, homocysteine upregulates the enzyme PKM2, which induces MHCII-related and costimulatory molecule gene expression in B cells, thereby increasing their antigen presentation function. The gene discussed is PKM; the disease is atherosclerosis.