sentences:  Th1 responses appeared to be normal in these patients.The susceptibility of these children to mycobacterial infections thus apparently results from an intrinsic impairment of the IFNγ pathway response to these particular intracellular pathogens, showing that IFNγ is obligatory for efficient macrophage antimycobacterial activity.Since the initial discoveries of IFNγR1-deficient humans, many more examples have been found, and IFNγR2-deficient individuals have been found as well.