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The specific antibody response to O, H and Vi antigens, levels of IgG, IgM, IgA and C3, presence of soluble immune complexes, in vitro tests of cellular immunity and subsets of lymphocytes in the peripheral blood were investigated in human volunteers after a single dose of 0.1 ml intradermal typhoid vaccination. The results indicated that typhoid vaccination induced antibody formation, slightly increased IgA levels and led to a decrease in C3 which was probably due to immune complex formation. There was also a relative increase in circulating Fc-IgG receptor-bearing lymphocytes and T-gamma cells after vaccination. In those subjects who showed specific cellular immunity before vaccination, a transient depression in lymphocyte transformation and a negative leucocyte migration inhibition test with typhoid baccilli occurred post-vaccination. These findings raise doubts over the advantages of giving typhoid vaccine during an epidemic. [ABSTRACT FROM AUTHOR]

The development of the cell-mediated immune response (CMIR) to antigens prepared from Salmonella typhi was investigated in patients suffering from typhoid fever and in normal healthy subjects. The leucocyte migration inhibition test, blast transformation of lymphocytes and active rosette-forming cells were used for detecting CMIR. Peripheral blood lymphocytes were analysed for the numbers and proportions of B lymphocytes, T lymphocytes and their subpopulations with receptors for IgM (Tμ) or IgG (Tγ) and cells with Fc receptors for IgG. These parameters were correlated with the duration and the severity of illness. The uncomplicated cases of typhoid fever were found to have an intact CMIR as compared to the complicated cases. The ratio of T lymphocyte subpopulations was grossly imbalanced in typhoid patients, the numbers of T lymphocytes and their subpopulations were further altered in the complicated cases as compared to uncomplicated cases. The present study demonstrates a depressed state of CMIR in complicated patients with typhoid fever. CMIR may thus emerge as the cardinal point for recovery in typhoid fever rather than the specific antibodies. The study further demonstrates that imbalance within the subsets of T lymphocytes may be responsible for the depressed state of CMIR in complicated cases of typhoid fever. [ABSTRACT FROM AUTHOR]

The development of O, H and Vi antibodies to Salmonella typhi antigens, immunoglobulins and C3 levels, and the presence of rheumatoid factor and circulating immune complexes were determined in the sera of patients with typhoid fever and appropriate age- and sex-matched controls. IgM, and both O and H antibodies were raised in typhoid patients. Rheumatoid factor, a possible indicator of persistent circulating immune complexes, was also present in these patients. Immune complexes were more often present in patients with typhoid fever than in controls, their presence was much more marked in complicated cases of typhoid fever. A high ratio of α1-antitrypsin to C3 was found in these patients suggesting complement consumption. [ABSTRACT FROM AUTHOR]