Morphological differentiation of human lymphocyte subpopulations following polyclonal stimulation with bacteria and lectin.

Mononuclear cells (MNC) were stimulated with different heat-treated gram-positive and -negative bacteria, and the lymphocyte subpopulation interaction, the proliferative response, and the immunoglobulin secretion were analyzed. It can be demonstrated that beta haemolytic streptococci and Staphylococcus aureus have a similar stimulation pattern: early stimulation of helper T cells, cell contacts of helper T cells and B cells, maximum proliferation on day 5 and 7, and Ig secretion peak on day 7. Klebsiella pneumoniae and Yersinia enterocolitica do not cause proliferation, while Ig secretion is seen on day 5. No cell contacts and no T cell stimulation are seen in the Klebsiella culture, whilst Yersinia causes slight helper T cell activation. In contrast, PHA induces strong T cell stimulation, proliferation and expansion of the suppressor T cell subpopulation. Leu 7-positive lymphocytes are not activated by any of these stimulants.