臨床感染症と実践

抽象的な

Killer Cell Immunoglobulin like Receptors (KIR) Gene Variations in Rheumatic Fever and Rheumatic Heart Disease Patients from North India

Sarkar S ,Rastogi M ,Kumar R ,Chakraborti A *

The autoimmune sequelae of rheumatic fever (RF) and rheumatic heart disease (RHD) are due to untreated or partially treated pharyngitis caused by Group A streptococcus (GAS). RF/RHD usually affects the genetically susceptible individuals. KIR (Killer cell immunoglobulin like receptor) of NK (natural killer) cell has been documented in susceptibility to various autoimmune diseases. KIR is of activating, inhibitory, pseudo and framework types. In here, 29 patients (pharyngitis, RF and RHD) and controls were studied to establish the association of different KIR genes in development of RF/RHD. KIR genotyping in all the disease groups revealed that the frequency of activating KIR2DS4A and inhibitory KIR2DL5B were less in RHD compared to the control. On the other hand, frequency of activating KIR2DS5A was more in RHD than pharyngitis. A significant difference in the frequency of KIR2DS2A and KIR3DL1B were found in pharyngitis compared to control. Interestingly, the overall data revealed a marked decrease of activating genes in pharyngitis and an increase in RHD. However, in the study, the framework genes were comparatively conserved and pseudo genes did not show any significant change. Thus, the study suggests an association of KIR in the pathogenesis of RF/RHD by demonstrating the variations in specific genotypes. This can be correlated to the prolonged activation of NK cells which may be accountable for regulation of adaptive immune response and self-tolerance. Further study in large cohort may unveil more information regarding the role of KIR in the development of the disease.