IMMUNODEFICIENCY IN NONTUBERCULOUS MYCOBACTERIAL DISEASE

T-cell immunity was investigated in eight patients with non-tuberculou s mycobacterial disease, to see whether impaired immune function might be the explanation for their infection. Cellular immune function was evaluated in vitro by measuring the proliferation of peripheral blood mononuclear cells in response to both non-specific mitogens (phytohaem agglutinin and pokeweed mitogen) and specific recall antigens (strepto kinase-streptodornase and purified protein derivative from Mycobacteri um tuberculosis), and in vivo, by measuring the skin test response to a panel of recall antigens. Functionally relevant T-lymphocyte sub-pop ulations (CD4, CD8, activated CD3 and gamma/delta T-cells) were enumer ated by two-colour flow cytometry. The results were compared with thos e for a group of patients with pulmonary tuberculosis, with groups of controls matched for age and smoking habit, and with a patient group r eceiving steroid treatment. The patients with non-tuberculous mycobact erial disease had poor or absent skin test responses; in vitro, their response to recall antigens was depressed, although their response to mitogens was normal. The patients had significantly raised levels of C D8 lymphocytes and activated T-cells, but lacked any circulating gamma /delta T-cells. There were also differences between the various contro l groups. In conclusion, this study demonstrates a deficiency in the c ellular immune system of these patients, which is most readily detecta ble by skin testing, or by measuring lymphocyte proliferative response s to recall antigens. However, the study also shows changes in cellula r immune responses in controls matched for age and smoking and in pati ents on steroid treatment, and underscores the need for matched contro ls. Further work needs to be done to ascertain whether the cellular im mune deficiency is a cause of, or is caused by, the mycobacterial infe ctions, and also to investigate the pathological significance of the a lterations in T-cell sub-populations.