Immunological screening of welders

74 healthy welders were subjected to immunological screening. Serum immunoglobulins (IgG, IgA, IgM) were measured as well as total and active E-RFC and cellular immunity was evaluated using the intradermal testing of PPD, candidin D-7, trichophytin D-5 and tetanus anatoxin. The obtained results suggest suppression of the T and B lymphocyte immune systems as expressed by decreased levels of serum IgG and total E-RFC. Cell-mediated immune deficiency was found in 21.6% welders. Suppression of the immune system may be accounted for by a complex effect of occupational factors, such as manganese compounds, vibration and noise.