The role of T, B and adherent cells in the in vitro immune response of TEPC-183-bearing mice

Abstract

In order to analyse the mechanism of immunosuppression of plasmacytoma-bearing mice, the role of enriched T cells, B cells, and adherent cells from the spleens of normal and TEPC-183 plasmacytoma (IgM,k) bearing mice in the primary in vitro immune response was investigated. Nylon-wool-enriched fractions of T and B cells were used in the study of T-cell-dependent immune responses to the 2-4-6-trinitrophenyl ligand. When 5 × 10^-5 M 2-mercaptoethanol (2-ME) was present in cultures, TEPC-183 spleen cells or their T- or B-cell-enriched fractions did not suppress the immune responses of normal spleen cells. However, in the absence of 2-ME, T- or B-cell fractions were as effective as unfractionated TEPC-183 spleen cells in causing suppression of normal immune responses.

T and B cells derived from TEPC-183 spleens gave minimal anti-trinitrophenyl specific plaque-forming-cell responses when co-cultured with adherent cells from either normal or TEPC-183 spleens. In contrast, either T- or B-cell fractions from TEPC-183 spleens were at least partially competent when co-cultured with B or T cells from normal spleens. The data thus suggest that the suppressed state of TEPC-183 spleen cells may be due to defective T—B cell interaction. It was consistently observed that splenic adherent cells from TEPC-183-bearing mice were neither suppressed nor suppressive for the in vitro immune responses of normal splenic lymphocytes at the ratios tested. Adherent peritoneal exudate (PE) cells from either normal or TEPC-183-bearing mice were equally suppressive for the in vitro immune responses of normal splenic lymphocytes at the PE cell to lymphocyte ratios of 1:10 and 1:35. Thus, the suppressive characteristic of adherent PE cells in this system is not specific for TEPC-183 plasmacytoma in mice.

TEPC-183 spleens were found to contain 35% or more esterase-positive cells, compared with approximately 5% esterase-positive cells present in normal spleens. The possible role of esterase-positive cells, T cells, B cells, and adherent cells in the observed suppression will be discussed.