Cell-populations involved in the humoral leukocyte adherence inhibition reaction. The T8-suppressor/cytotoxic cells are both effectors and responders.

In an attempt to identify the cell subpopulation involved in the humoral leukocyte adherence inhibition (H-LAI) reaction, mononuclear leukocytes were fractionated and the response with the different cell populations was measured in the H-LAI assay using sera from lung cancer patients and a lung cancer associated antigen. The monocytes were found to exhibit a suppressive effect on the H-LAI response. The B-lymphocytes seemed not to take an active part in the reaction. Depletion of the T-lymphocytes abolished the reaction. Subsequent studies on the T-lymphocyte subpopulations revealed that removal of the T4-cells had little effect while removal of the T8-cells resulted in complete abrogation of the H-LAI response. Direct blocking by monoclonal antibodies against the T4 and T8 surface determinants gave additional support for the T8-cell dependency of the H-LAI assay. The cells that specifically were induced to loose adherence in the H-LAI assay upon incubation with serum from a lung cancer patient and lung cancer associated antigen were also analyzed. Compared to the total mononuclear leukocyte population, the relative content of monocytes and B-cells were lower in the non-adherent population. An increase was found in the relative number of T-cells. While the relative number of T4-cells decreased, the content of T8-cells was significantly increased. Furthermore, a direct correlation was found between the loss of adherence of the T8-subpopulation and the index of the H-LAI response. The present study indicates the T8-subpopulation of the T-lymphocytes to be involved both in the effector and responder side of the H-LAI reaction and gives implications for an immunological reaction behind the response of the H-LAI assay.