Several alterations in immune responses contribute to the risk of recurrent group A Streptococcustonsillitis (“strep throat”); researchers report. Recurrent tonsillitis is a common indication for tonsillectomy, yet it remains unclear why some children get group A Streptococcus (GAS) recurrent tonsillitis and others do not. Dr. Shane Crotty from La Jolla Institute for Immunology and the University of California, San Diego, and colleagues compared immunological characteristics of 26 children with recurrent GAS tonsillitis and 39 control children without recurrent tonsillitis who were undergoing tonsillectomies.
Germinal centers in tonsils from recurrent tonsillitis children had significantly fewer T follicular helper cells and B cells than did those from control children; Because the team reports in the February 6 issue of Science Translational Medicine. Recurrent tonsillitis was also associated with impaired development of antibodies against streptococcal pyrogenic exotoxin A (SpeA), a GAS virulence factor.
Children with recurrent tonsillitis experienced 12 times more tonsillitis episodes than controls; therefore which should have resulted in substantially more GAS-specific CD4+ T cells. Because Instead, children with recurrent tonsillitis had a lower ratio of GAS-specific T follicular helper cells to total GAS-specific CD4+ T cells; suggesting that GAS-specific germinal center T follicular helper cell responses are deficient in recurrent tonsillitis.
Rheumatic heart disease.
Compared with control children, children with recurrent tonsillitis were less likely to have human leukocyte antigen class II allele (HLA) DQB1*06:02, likely a protective allele against GAS recurrent tonsillitis; and more likely to have HLA DRB1*01:01 and DRB1*07:01; which have been linked to an increased risk of rheumatic heart disease.
CD4+ T cells from HLA DQB1*06:02-positive individuals showed enhanced binding and more robust responses to GAS and the GAS superantigen SpeA, compared with those from HLA DQB1*06:02-negative individuals. SpeA was also capable of deviating germinal center T follicular helper cells into killer cells; a pathological feature of recurrent tonsillitis.
“Together; these results reveal that altered adaptive immune responses to group A Streptococcus may differentiate those at risk of recurrent infection;” the researchers conclude. Because “These findings have several implications; including the plausibility of SpeA as a potential vaccine target for recurrent tonsillitis and strep throat generally.”
The immune system protects the body from possibly harmful substances by recognizing and responding to antigens. Antigens are substances (usually proteins) on the surface of cells; viruses, fungi, or bacteria. Nonliving substances such as toxins, chemicals, drugs, and foreign particles (such as a splinter) can also be antigens.
The immune system recognizes and destroys, or tries to destroy, substances that contain antigens. Therefore Your body’s cells have proteins that are antigens. These include a group of antigens called HLA antigens. Your immune system learns to see these antigens as normal and usually does not react against them.