De novo CD5+ diffuse large B cell lymphoma with basophilia in the peripheral blood: successful treatment with autologous peripheral blood stem cell transplantation

How I investigate basophilia in daily practice

Basophilia is a rare disorder of the complete blood count (CBC) and its management in daily practice remains unclear. Two main factors explain this situation. On the one hand, the reliability of the basophil count is insufficient, whether it is performed by a microscopic slide examination or by a hematology analyser. On the other hand, our knowledge of conditions associated with basophilia is largely based on few case reports and on reviews that refer to older reviews. The association between basophilia and myeloid neoplasm, especially chronic myeloid neoplasm, is well established. Conversely, there are conflicting data on some benign medical conditions and it remains unclear where basophilia may be present. In this review, we have investigated the medical literature to define which medical conditions can lead to basophilia and which cannot, and we propose a practical approach to manage basophilia divided into 3 steps. First, we have to check the real existence of the basophilia by getting rid of spurious basophilia. Then, we have to look for symptoms that suggest reactive basophilia and for clue of a neoplastic cause. Finally, in case of suspicion of a myeloid neoplasm or persistence of the basophilia in the absence of a reactive cause, we have to decide which examinations need to be prescribed to confirm a neoplastic basophilia.

Mast cells, basophils and B cell connection network

It has been proven that both resting and activated mast cells (MCs) and basophils are able to induce a significant increase in proliferation and survival of naïve and activated B cells, and their differentiation into antibody-producing cells. The immunological context in which this regulation occurs is of particular interest and the idea that these innate cells induce antibody class switching and production is increasingly gaining ground. This direct role of MCs and basophils in acquired immunity requires cell to cell contact as well as soluble factors and exosomes. Here, we review our current understanding of the interaction between B cells and MCs or basophils as well as the evidence supporting B lymphocyte-MC/basophil crosstalk in pathological settings. Furthermore, we underline the obscure aspects of this interaction that could serve as important starting points for future research in the field of MC and basophil biology in the peculiar context of the connection between innate and adaptive immunity.