Understanding T-cell memory

Researchers report in the in the April 23 Science that the reason some T cells survive the T-cell die-off following infection clearance—and therefore provide long-term protection against infection—is the expression of a specific form of CD8.

The work got its start in the mucosal lining of the intestine. “In a previous study… we discovered that a molecule, CD8aa, is expressed on the mucosal T cells but not on other T cells,” said Hilde Cheroutre of the La Jolla Institute for Allergy and Immunology and senior author of the study.

T cells can express two CD8 molecules: CD8aß and CD8aa. According to Cheroutre, one control for this study was using T cells from the spleen because they do not normally express CD8aa. But to the group's surprise, spleen T cells transiently expressed CD8aa upon activation.

“At first we were not so happy with this, but I decided to get to the ...