Major histocompatibility complex class I and class II antigen expression in diffuse large cell and large cell immunoblastic lymphomas. Absence of a correlation between antigen expression and clinical outcome.

The major histocompatibility complex (MHC) class I (HLA-A, B, C) and class II (HLA-DR) antigens are involved in cell-to-cell recognition and in regulating the immune response. Others have shown previously that MHC class I and class II antigens may be absent in a subset of malignant lymphomas, prompting the hypothesis that the absence of MHC antigen expression may be one of the mechanisms involved in the growth and dissemination of malignant lymphomas (by allowing a neoplasm to escape immune surveillance). To address this hypothesis, we analyzed MHC class I and class II (HLA-DR) antigen expression by diffuse large cell and large cell immunoblastic lymphomas in 88 and 117 patients, respectively, using frozen sections and the monoclonal antibodies W6/32 (HLA-A, B, C), anti-beta 2-microglobulin, and L203 (HLA-DR). Although there were no statistically significant clinical differences by MHC class II antigen expression, a small group of patients with MHC class I antigen-negative lymphomas were significantly younger (P = 0.03), less often had small neoplasms (P = 0.03), and were treated with doxorubicin-based chemotherapy more frequently (P = 0.04) than those with antigen-positive lymphomas. However, neither MHC class I nor class II antigen expression by the lymphomas consistently correlated with patient survival or freedom from relapse. This lack of correlation was true for all patients assessed, as well as for the subsets of patients with B-cell lymphomas, T-cell neoplasms, or those treated with doxorubicin-based chemotherapy. In accordance with previously published studies, stage, presence of B symptoms, and treatment with doxorubicin-based chemotherapy were of prognostic importance in univariate or multivariate analyses for survival or freedom from relapse. The findings may be considered evidence against the hypothesis that the absence of MHC class I or II antigen expression by malignant lymphomas plays a role in their tumorigenicity. However, we cannot completely exclude the possibility that the therapies used for this group of patients may have obscured any effect that MHC antigen expression exerts on prognosis.