Decline in beta-2 microglobulin levels after antitubercular therapy in tubercular patients with HIV infection

Infection with Mycobacterium tuberculosis results in a state of immune activation, more so, when there is concomitant HIV infection. Beta-2 microglobulin (B2M) is a useful marker to study the state of immune activation among the HIV infected. Objective. To study the modulation of B2M levels among patients with HIV/TB coinfection, to correlate it with the CD4 count and also to study the change in these levels after four weeks of therapy.

Twelve patients with HIV infection and having concomitant TB diagnosed on the basis of positive acid fast bacilli were studied both at baseline and then at four weeks. Fourteen HIV infected individuals who had no overt opportunistic infection at the time of the study were also studied along with fourteen age and sex matched healthy volunteers. CD4 counts were performed using a flowcytometer. B2M was measured using a commercially available ELISA kit.

B2M levels in HIV/TB coinfected patients were 1.62+/-0.45 mg/L (range 1-2.7 mg/L) and were significantly higher (p<0.0002) when compared with healthy controls, whose levels were 0.74+/-0.05 mg/L (range 0.48-81 mg/L). The levels in HIV infected individuals free of opportunistic infections were 1.2+/-0.16 mg/L (range 0.78-1.92 mg/L) and were significantly lower than the levels in HIV/TB coinfected (p<0.017), but significantly higher than the levels in healthy controls (p<0.01). Four weeks of antitubercular therapy resulted in a decline in B2M to 1.08+/-0.26 mg/L (range 0.8-1.74 mg/L) and was statistically significant (p<0.012). There was no correlation between the CD4 counts and the pre-treatment levels of B2M among these patients.

Patients with HIV/TB coinfection had significantly higher levels of B2M than individuals with HIV infection without associated opportunistic infection and healthy controls. Four weeks of anti-tuberculous therapy resulted in a significant decline in these levels.