Immune response to S treptococcus pneumoniae in asthma patients: comparison between stable situation and exacerbation

Summary In A rgentina, more than 3 million people suffer from asthma, with numbers rising. When asthma patients acquire viral infections which, in turn, trigger the asthmatic response, they may develop subsequent bacterial infections, mainly by S treptococcus (S.) pneumoniae . This encapsulated G ram + bacterium has been considered historically a T cell‐independent antigen. Nevertheless, several papers describe the role of T cells in the immune response to S . pneumoniae . We evaluated the response to S . pneumoniae and compared it to the response to M ycobacterium (M.) tuberculosis , a different type of bacterium that requires a T helper type 1 ( Th 1) response, in cells from atopic asthmatic children, to compare parameters for the same individual under exacerbation and in a stable situation whenever possible. We studied asthma patients and a control group of age‐matched children, evaluating cell populations, activation markers and cytokine production by flow cytometry, and cytokine concentration in serum and cell culture supernatants by enzyme‐linked immunosorbent assay ( ELISA) . N o differences were observed in γδ T cells for the same patient in either situation, and a tendency to lower percentages of CD 4 + CD 25 hi T cells was observed under stability. A significantly lower production of tumour necrosis factor ( TNF) ‐α and a significantly higher production of interleukin ( IL) ‐5 was observed in asthma patients compared to healthy individuals, but no differences could be observed for IL ‐4, IL ‐13 or IL ‐10. A greater early activation response against M . tuberculosis , compared to S . pneumoniae , was observed in the asthmatic patients' cells. This may contribute to explaining why these patients frequently acquire infections caused by the latter bacterium and not the former.