Activating and inhibitory CD94/NKG2 receptors regulate CTL responses by altering TCR signaling, thus modifying antigen activation thresholds set during thymic selection. To determine whether their expression was linked to TCR specificity, we examined the TCR repertoire of oligoclonal CTL expansions found in human blood and tissues. High-resolution TCR repertoire analysis revealed that commitment to inhibitory NKG2A expression was a clonal attribute developmentally acquired after TCR expression and during antigen encounter, whereas actual surface expression depended on recent TCR engagement. Further, CTL clones expressing sequence-related TCR, and therefore sharing the same antigen specificity, invariably shared the same NKG2A commitment. These findings suggest that TCR antigenic specificity dictates NKG2A commitment, which critically regulates subsequent activation of CTL.

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Coptotermes formosanus is an imported, subterranean termite species with the largest economic impact in the United States. The frontal glands of the soldier caste termites comprising one third of the body mass, contain a secretion expelled through a foramen in defense. The small molecule composition of the frontal gland secretion is well-characterized, but the proteins remain to be identified. Herein is reported the structure and function of one of several proteins found in the termite defense gland secretion. TFP4 is a 6.9 kDa, non-classical group 1 Kazal-type serine protease inhibitor with activity towards chymotrypsin and elastase, but not trypsin. The 3-dimensional solution structure of TFP4 was solved with nuclear magnetic resonance spectroscopy, and represents the first structure from the taxonomic family, Rhinotermitidae. Based on the structure of TFP4, the protease inhibitor active loop (Cys8 to Cys16) was identified.

TCR Specificity Dictates CD94/NKG2A Expression by Human CTL One of the figures in this article (Immunity 17, 487-499, October 2002), Figure 6, had an error in it. Therefore we are printing the correct figure here.

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