Selective IgM Deficiency with T Cell Defects and Mycobacterium Avium Complex (MAC) Infection

Primary selective IgM deficiency in adults is associated with normal T cell function, and patients clinically manifest with recurrent pyogenic bacterial infections. In this study, we present three patients with selective IgM deficiency with significant defects in T cells and NK cell cytotoxicity, and Mycobacterial avium intracellulare (MAC) infection. T cell defect is characterized by markedly reduced numbers of T cells and T cell subsets, decreased T cell proliferative responses to mitogens and antigens, including PPD, and significantly decreased production of IFN- ; however, expression of IFN- receptors is normal. We propose that selective IgM deficiency with significant T cell functional defects might represent a distinct clinical entity, which is associated with increased susceptibility to MAC infection.