Influence of HLA-DR2 phenotype on humoral immunity & lymphocyte
response to Mycobacterium tuberculosis culture filtrate antigens in
pulmonary tuberculosis
Association of HLA-DR2 genes/gene products has been shown with pulmonary tuberculosis (PTB)
patients in India. In the present study, the influence of HLA-DR2 and non-DR2 genes/gene products
on immunity to tuberculosis has been studied. Plasma samples of -DR2 positive patients (active and
inactive TB) showed a higher antibody titre to Mycobacterium tuberculosis culture filtrate antigens
than non-DR2 (-DR2 negative) patients. Immunoblot analysis revealed a trend towards an increased
percentage of DR2 positive patients recognizing 38, 32/34 and 30/31 kDa antigens of M. tuberculosis
than DR2 negative patients. A low spontaneous lymphoproliferative response (without antigen
stimulation) was seen in HLA-DR2 positive active TB patients than HLA-DR2 negative patients.
However, the antigen stimulated lymphocyte response was higher in the -DR2 positive patients (active
and inactive TB) when compared to non-DR2 patients. Further, an inversional correlation between
antibody titre and spontaneous as well as antigen induced lymphocyte response (measured by 3H
thymidine uptake and expressed as counts per minute) was seen in HLA-DR2 positive active PTB
patients than non-DR2 patients. The present study suggests that HLA-DR2 genes/gene products may
be associated with a regulatory role in the mechanism of disease susceptibility to tuberculosis. The
genes while augmenting the humoral immune response, they suppress the spontaneous and antigen
induced lymphocyte response in -DR2 positive patients with active disease.
Key words Antigen recognition - HLA-DR2-antibody titre - lymphocyte response - Mycobacteriu
