015 Citation: Elkhalifa S, Garcez T, Drinkwater S, Tan T, Vijayadurai P, et al. (2021) First case series of clozapine induced hypogammaglobulinaemia in England. Ann Psychiatry Treatm 5(1): 015-018. DOI: https://dx.doi.org/10.17352/apt.000025 https://dx.doi.org/10.17352/apt DOI: 2640-8031 ISSN: MEDICAL GROUP Introduction Schizophrenia is a debilitating psychiatric condition and clozapine is recommended for patients who are unresponsive to, or intolerant of, conventional antipsychotic drugs [1]. Clo- zapine has numerous possible side-effects, 1 among which neu- tropenia and fatal agranulocytosis are well-documented [2]. More recently, an association between clozapine treatment and hypogammaglobulinaemia has been reported [3]. Among four clinical immunology centres in the north west of England, we identified 17 clozapine-treated patients who were referred with hypogammaglobulinaemia for which there was no other likely cause. We describe the clinical and immu- nological phenotypes of these patients, and their management. Additionally, we speculate that a possible mechanism for this drug side-effect is interaction with PI3 kinase pathways in- volved in the development and maturation of B cells. Aim To review the diagnosis and management of hypogamma- globulinaemia in patients on long-term clozapine treatment. Method Retrospective review of medical notes and electronic pa- tient records was undertaken to obtain information on the fol- lowing: 1. Demographics 2. Immunoglobulin levels (IgG, IgA & IgM), serum elec- trophoresis and immunofixation 3. Lymphocytes subsets (CD4, CD8, CD19 and CD16/56) 4. Specific antibody serology and response to vaccination, when relevant. 5. Mannose binding lectin (MBL) levels. Abstract Evidence is emerging that clozapine can adversely affect immunoglobulin levels. We present a case series of 17 clozapine-treated patients referred to clinical immunology centres in the north west of England with otherwise-unexplained hypogammaglobulinaemia. This adds to existing evidence and suggests that clozapine can cause clinically significant antibody deficiency that will sometimes require specialist intervention. We speculate that this putative drug toxicity could be mediated via interaction with PI3K (phosphatidylinositol-3-kinase) signalling pathways involved in the development and homeostasis of B cells. It may be advisable to monitor immunoglobulin levels in patients being treated with clozapine. Research Article First case series of clozapine induced hypogammaglobulinaemia in England S Elkhalifa 1 *, T Garcez 2 , S Drinkwater 2 , T Tan 1 , P Vijayadurai 3 , A Anantharachagan 3 , A Herwadkar 1 , H Alachkar 4 and J Darroch 4 1 Salford Royal NHS Foundation Trust, England 2 Manchester University NHS Foundation trust, England 3 Lancashire Teaching Hospitals NHS Foundation Trust, England 4 Royal Liverpool and Broadgreen University Hospitals NHS Trust, England Received: 16 February, 2021 Accepted: 17 March, 2021 Published: 18 March, 2021 *Corresponding author: Dr. Shuayb Elkhalifa, Consultant Immunologist, Salford Royal NHS Foun- dation Trust, Salford Care Organisation, Honorary Lecturer, Faculty of Biology, Medicine and Health, University of Manchester, England, E-mail: Keywords: Clozapine; Hypogammaglobulinaemia; Phosphatidylinositol-3-kinase; Humoral immune deficiency; B cells https://www.peertechzpublications.com