Abstract
Diffuse Large B Cell Lymphoma (DLBCL) and Follicular Lymphoma (FL) are the most common adult low-grade non Hodgkin’s lymphomas. The influence of these diseases in peripheral blood lymphocytes is not well defined. Indeed the lymphocytic arrangement can be altered on account of the leukaemic form (although it slightly ever occurs); on the other hand the cause of occasional anomalies can be the involvement of the immune system against neoplasm. In order to contribute to the knowledge of these conditions we have analysed, at diagnosis, the lymphocytic immunophenotype in peripheral blood of 61 subjects: 27 were affected by DLBCL, average age 68, and 34 by FL, average age 61 years. Therefore we quantified the number of lymphocytes and evaluated essential markers, using flow cytometry, to define T, B, NK subsets by: CD3, CD4, CD8, CD19, SIgk, Sigl, CD56, and expression of CD11a molecule on T CD8. The absolute peripheral blood lymphocytes count presented a reduction in 51% and in 32% of the cases with an increase in 4% and in 3% of the subjects respectively considering DLBCL and FL. On the contrary T cells (CD3) had similar decrease, 33% and 32%, and different augmentation 15% and 3%. T cells ratio CD4/CD8 was under normal in 23% and in 12% of the patients but over normal in 12% and 29% always in DLBCL and FL. B cells (CD19) were reduced in 35% and in 12% of the subjects but increased in 8% and in 14%, whereas clonal restriction was present in 8% and in 20% of the components of the two groups. Natural Killer lymphocytes (CD56) were under normal in 12% and in 6% of bthe cases but over in 40% and 20%. Finally CD11a was over-expressed in 87% and in 68% of the patients of the respective pathologies. After selecting patients aged over 60 years, following four parameters that showed a significant variability was obtained: 1) lymphopenia in 50% of the cases in both groups; 2) similar results 11% and 15% about clonal restriction; 3) increase of the NK population 42% and 30% in DLBCL and FL; 4) very high over-expression of CD11a on T CD8 of 90% and 80%. Therefore DLBCL and FL are lymphoproliferative diseases where there is an important subtraction of lymphocytes, particularly in elderly people, from peripheral blood (perhaps because of accumulation in lymphnodes). These lesions present clonal restriction of B cells only in few cases (confirming the low known leukaemic form) while Natural Killer population are well represented especially in DLBCL. The over-expression of CD11a is the most altered parameter and seems almost a typical marker of these diseases above all in over 60 years subjects. Consequently if rarely happens that a leukaemic form of DLBCL and FL are found by flow cytometry however immunological defined alterations are very frequent in most of the cases of old patients.
PD-L1 over-expression is driven by B-cell receptor signaling in diffuse large B-cell lymphoma
