Liver steatosis, the earliest stage of metabolic-associated non-alcoholic fatty liver disease (MAFLD), is the most common form of liver damage. However, the specific immune response linked to this condition remains poorly understood. This study aimed to assess immune system parameters and their relationships in patients with cardiorheumatic diseases who also have metabolic-associated liver steatosis (MALS). A total of 53 patients were included in the study: 32.07% had ischemic heart disease, 39.62% had haemorrhagic vasculitis, and 28.31% had rheumatic fever. Various immune parameters were measured, including different lymphocyte subtypes, immunoglobulin levels, immune complexes, complement components, and phagocyte activity. In patients with MALS, immune disturbances were characterized by significant shifts in B-cell activity, elevated immune-effector indices, increased small immune complexes, and complement component levels. Low-affinity B-cells emerged as central in immune system interactions, showing significant correlations with various immune cells, such
as T-cells, T-suppressors, NK cells, and IL-2 receptor-bearing T-cells, as well as with the immunoeffector index. Key immune mechanisms associated with MALS included activation of the humoral immune response, the complement system, immune complex formation, and enhanced antibacterial activity in phagocytes.