CD38 regulates chronic lymphocytic leukemia proliferation via CD45 phosphatase activity.

Chronic lymphocytic leukemia (CLL) growth is dependent on both B cell receptor (BCR) signaling and signals from microenvironmental T helper (Th) cells. We previously described a mechanism where Th cells enhance BCR signaling and proliferation through CD45 phosphatase activity regulation via galectin-1 and CD43. The CLL negative prognostic indicator CD38 is linked to BCR signaling and proliferation, with its expression induced by Th cells.

Tetraspanin CD53 controls T cell immunity through regulation of CD45RO stability, mobility, and function.

T cells depend on the phosphatase CD45 to initiate T cell receptor signaling. Although the critical role of CD45 in T cells is established, the mechanisms controlling function and localization in the membrane are not well understood. Moreover, the regulation of specific CD45 isoforms in T cell signaling remains unresolved.

T-helper cell regulation of CD45 phosphatase activity by galectin-1 and CD43 governs chronic lymphocytic leukaemia proliferation.

Chronic lymphocytic leukaemia (CLL) is characterised by malignant mature-like B cells. Supportive to CLL cell survival is chronic B-cell receptor (BCR) signalling; however, emerging evidence demonstrates CLL cells proliferate in response to T-helper (Th) cells in a CD40L-dependent manner. We showed provision of Th stimulation via CD40L upregulated CD45 phosphatase activity and BCR signalling in non-malignant B cells.

Integration of T helper and BCR signals governs enhanced plasma cell differentiation of memory B cells by regulation of CD45 phosphatase activity.

Humoral immunity relies on the efficient differentiation of memory B cells (MBCs) into antibody-secreting cells (ASCs). T helper (Th) signals upregulate B cell receptor (BCR) signaling by potentiating Src family kinases through increasing CD45 phosphatase activity (CD45 PA). In this study, we show that high CD45 PA in MBCs enhances BCR signaling and is essential for their effective ASC differentiation.

The Imbalance of Circulating Follicular T Helper Cell Subsets in Primary Sjögren's Syndrome Associates With Serological Alterations and Abnormal B-Cell Distribution.

Since B-cell hyperactivity and pathologic antibody response are key features in the immunopathogenesis of primary Sjögren's syndrome (pSS), the role of follicular T helper (T) cells as efficient helpers in the survival and differentiation of B cells has emerged. Our aim was to investigate whether a change in the balance of circulating (c)T subsets and follicular regulatory T (T) cells could affect the distribution of B cells in pSS. Peripheral blood of 38 pSS patients and 27 healthy controls was assessed for the frequencies of cT cell subsets, T cells, and certain B cell subpopulations by multicolor flow cytometry.