RESUMO
A marked elevation of serum IgE level (6939 +/- 5651 IU/ml) was observed in 20 untreated and drug sensitive patients with sputum AFB positive pulmonary tuberculosis. Of them 18 were freshly diagnosed and were totally untreated. Their mean serum IgE level was 6715 +/- 5545 IU/ml. The remaining two patients presented with a relapse of the disease but were sensitive to all anti-tuberculosis drugs. Their serum IgE levels before retreatment were 2828 and 15079 IU/ml respectively. In the 13 chronic drug resistant patients who never had sputum conversion, the serum IgE level (1116 +/- 1897 IU/ml) was significantly lower (P < 0.01). It is suggested that the high serum IgE response in freshly diagnosed untreated and drug sensitive patients with illness of short duration may be related to strong early tuberculin hypersensitivity reaction and protective immunity, whereas low serum IgE response in chronic drug resistant cases with high bacterial load for prolonged duration may be related to the generation of suppressor CD8 lymphocytes eventually leading to suppression of B cells committed to the synthesis of protective serum IgE.