Anti-T cell globulin (ATG) is polyclonal IgG from rabbits immunized with human thymocytes or a human T cell line. Prophylaxis using ATG infused with conditioning for adult marrow or blood stem cell transplantation reduces both acute and chronic graft-versus-host disease (GVHD). However, ATG is not or minimally efficacious in steroid refractory GVHD treatment. Regarding preemptive therapy, ATG is promising; however, further work is needed on establishing adequate biomarkers to be used as triggers for preemptive therapy before it can be used routinely. Relapse is not increased by ATG, except possibly in the setting of reduced-intensity conditioning. Infections are probably increased when using high but not low-dose ATG, except for Epstein-Barr virus-driven post-transplantation lymphoproliferative disorder, which may be increased even with low-dose ATG. Survival is not improved with ATG; however, survival free of immunosuppressive therapy is improved. Pharmacokinetics of ATG are highly variable, resulting in highly variable areas under the time-concentration curves. Optimized dosing of ATG might improve transplantation outcomes. In conclusion, ATG reduces GVHD and, thus, may improve quality of life, without compromising survival.

Background: After hematopoietic cell transplantation (HCT), there is a prolonged period of immune deficiency. Objective: To review the recovery of immunity after HCT, including how it is influenced by the cellular contents of the graft, and therapeutic implications. Methods: Literature review using Medline. Results/conclusion: Whereas innate immunity (e.g., epithelial barriers, phagocytes, natural killer cells) typically recovers within weeks post-transplant, the recovery of adaptive immunity takes longer, months for B cells and years for T cells. The recovery is influenced by the graft contents. For example the number of CD34 cells given with the graft affects the tempo of neutrophil recovery, and the number of CD4 T cells given with the graft affects CD4 T cell counts post-transplant. Improved understanding of the relationship between graft contents and immune reconstitution could lead to graft engineering improving transplant outcomes.

The MS4A gene family in humans includes CD20 and at least 15 other genes. CD20 exists as homo-oligomers in the plasma membrane, however different MS4A proteins expressed in the same cell may hetero-oligomerize. Given the importance of CD20 in B-cell function and as a therapeutic target, we sought to explore the potential for CD20 hetero-oligomerization with other MS4A proteins. We investigated expression in primary human B-cells of the four MS4A genes previously shown to be expressed in human B-cell lines (MS4A4A, MS4A6A, MS4A7, MS4A8B), as well as two genes comprising the closely related TMEM176 gene family, with a view to identifying candidates for future investigation at the protein level. TMEM176A and TMEM176B transcripts were either not detected, or were detected at relatively low levels in a minority of donor B-cell samples. MS4A4A and MS4A8B transcripts were not detected in any normal B-cell sample. MS4A6A and MS4A7 transcripts were detected at low levels in most samples, however the corresponding proteins were not at the plasma membrane when expressed as GFP conjugates in BJAB cells. We also examined expression of these genes in chronic lymphocytic leukemia (CLL), and found that it was similar to normal B-cells with two exceptions. First, whereas MS4A4A expression was undetected in normal B-cells, it was expressed in 1/14 CLL samples. Second, compared to expression levels in normal B-cells, MS4A6A transcripts were elevated in 4/14 CLL samples. In summary, none of the MS4A/TMEM176 genes tested was expressed at high levels in normal or in most CLL B-cells. MS4A6A and MS4A7 were expressed at low levels in most B-cell samples, however the corresponding proteins may not be positioned at the plasma membrane. Altogether, these data suggest that CD20 normally does not form hetero-oligomers with other MS4A proteins and that there are unlikely to be other MS4A proteins in CLL that might provide useful alternate therapeutic targets.

Chronic GVHD (cGVHD) is an important complication of allogeneic hematopoietic cell transplantation (HCT). As preemptive therapy might be efficacious if administered early post transplant, we set out to determine whether cGVHD can be predicted from the serum level of a biomarker on day 7 or 28. In a discovery cohort of 153 HCT recipients conditioned with BU, fludarabine and rabbit antithymocyte globulin (ATG), we determined serum levels of B-cell-activating factor, vascular endothelial growth factor, soluble TNF-α receptor 1, soluble IL2 receptor α, IL5, IL6, IL7, IL15, γ-glutamyl transpeptidase, cholinesterase, total protein, urea and ATG. Patients with low levels of IL15 (<30.6 ng/L) on day 7 had 2.7-fold higher likelihood of developing significant cGVHD (needing systemic immunosuppressive therapy) than patients with higher IL15 levels (P<0.001). This was validated in a validation cohort of 105 similarly-treated patients; those with low IL15 levels had 3.7-fold higher likelihood of developing significant cGVHD (P=0.001). Low IL15 was not associated with relapse; it trended to be associated with acute GVHD and was associated with low infection rates. In conclusion, low IL15 levels on day 7 are predictive of cGVHD, and thus could be useful in guiding preemptive therapy.

Hematopoietic stem cell transplantation (SCT) is routinely offered to suitable candidates with high-risk or advanced acute lymphoblastic leukemia (ALL). In this report, we update our experience with SCT in patients with ALL with a novel conditioning regimen. A total of 44 patients with high-risk or advanced (greater than first complete remission) ALL in remission underwent SCT after myeloablative conditioning with fludarabine + busulfan + total body irradiation. The median follow-up of surviving patients was 4.3 years (range, 1.0-9.0 years). The cohort consists of 32 patients with high-risk disease (median age, 40 years; range, 19-64 years) and 12 patients with advanced disease (median age, 25 years; range, 19-65 years) who underwent SCT: 25 with a related donor (21 fully matched) and 19 with an unrelated donor (16 fully matched). The cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) was 53.2%, and that of grade III-IV acute GVHD was 20.6%. The incidence of chronic GVHD was 55%. The 100-day nonrelapse mortality was 13.6%. Five-year progression-free survival was 56.7%, and 5-year overall survival was 66.0%. Nine patients (20%) died in remission, 6 (14%) died after relapse, and 2 survived after a second SCT for relapsed disease. Outcomes were inferior in older patients with comorbidities compared with other patients.

Skin prick test (SPT) and fluorescence enzyme immunoassay (FEIA) are widely used for the diagnosis of Immunoglobulin-E (IgE)-mediated allergic disease. Basophil activation test (BAT) could obviate disadvantages of SPT and FEIA. However, it is not known whether BAT gives similar results as SPT or FEIA for aeroallergens.