The effects of cryopreservation on bacterial lipopolysaccharide (LPS)-induced interleukin-1 (IL-1) production by unfractionated mononuclear cells (MNCs), adherent cells (ACs), and nonadherent cells (NACs) were studied. Culture supernatants from cryopreserved cells contained significantly larger concentrations of IL-1 [MNCs, 211 +/- 50; ACs, 640 +/- 41; NACs, 116 +/- 19 U/ml (mean +/- SEM)] as compared with supernatants from fresh cells (69 +/- 22, 427 +/- 69, and 72 +/- 33 U/ml, respectively). In addition, supernatants obtained from cocultures of autologous fresh and frozen cells contained much less than the expected quantities of IL-1 (78 +/- 8%), indicating that suppressor cells in the fresh population are responsible for the decreased IL-1 content. The studies suggest that functional inactivation of cryosensitive suppressor monocytes is associated with an increase in IL-1 production by the other subset. The results provide further evidence that lack of active suppressor monocytes and increased IL-1 production may be responsible for the previously reported enhanced plaque-forming cell responses of cryopreserved cells from normal controls and from patients with lung cancer.