High titre neutralizing antibodies in response to SARS-CoV-2 infection require RBD-specific CD4 T cells that include proliferative memory cells.

Background: Long-term immunity to SARS-CoV-2 infection, including neutralizing antibodies and T cell-mediated immunity, is required in a very large majority of the population in order to reduce ongoing disease burden. Methods: We have investigated the association between memory CD4 and CD8 T cells and levels of neutralizing antibodies in convalescent COVID-19 subjects. Findings: Higher titres of convalescent neutralizing antibodies were associated with significantly higher levels of RBD-specific CD4 T cells, including specific memory cells that proliferated vigorously in vitro. Conversely, up to half of convalescent individuals had low neutralizing antibody titres together with a lack of receptor binding domain (RBD)-specific memory CD4 T cells. These low antibody subjects had other, non-RBD, spike-specific CD4 T cells, but with more of an inhibitory Foxp3+ and CTLA-4+ cell phenotype, in contrast to the effector T-bet+, cytotoxic granzymes+ and perforin+ cells seen in RBD-specific memory CD4 T cells from high antibody subjects. Single cell transcriptomics of antigen-specific CD4+ T cells from high antibody subjects similarly revealed heterogenous RBD-specific CD4+ T cells that comprised central memory, transitional memory and Tregs, as well as cytotoxic clusters containing diverse TCR repertoires, in individuals with high antibody levels. However, vaccination of low antibody convalescent individuals led to a slight but significant improvement in RBD-specific memory CD4 T cells and increased neutralizing antibody titres. Interpretation: Our results suggest that targeting CD4 T cell epitopes proximal to and within the RBD-region should be prioritized in booster vaccines.

Failure of alemtuzumab therapy in three patients with MOG antibody associated disease.

BACKGROUND: Myelin Oligodendrocyte Glycoprotein antibody-associated disease (MOGAD) is most classically associated in both children and adults with phenotypes including bilateral and recurrent optic neuritis (ON) and transverse myelitis (TM), with the absence of brain lesions characteristic of multiple sclerosis (MS). ADEM phenotype is the most common presentation of MOGAD in children. However, the presence of clinical phenotypes including unilateral ON and short TM in some patients with MOGAD may lead to their misdiagnosis as MS. Thus, clinically and radiologically, MOGAD can mimic MS and clinical vigilance is required for accurate diagnostic workup. CASE PRESENTATION: We present three cases initially diagnosed as MS and then treated with alemtuzumab. Unexpectedly, all three patients did quite poorly on this medication, with a decline in their clinical status with worsening of expanded disability status scale (EDSS) and an increasing lesion load on magnetic resonance imaging of the brain. Subsequently, all three cases were found to have anti-MOG antibody in their serum. CONCLUSIONS: These cases highlight that if a patient suspected to have MS does not respond to conventional treatments such as alemtuzumab, a search for alternative diagnoses such as MOG antibody disease may be warranted.