CD3 T Lymphocytes Count of Apparently Healthy Adult Individuals in Ekpoma, Edo State, Nigeria Babatope, I.O. 1* , Esumeh, F.I. 2 , Orhue, P.O. 1 , Amaechi, R.A. 1 , Inojie, V. 1 1 Department of Medical Laboratory Science, Faculty of Basic Medical Sciences, Ambrose Alli University, Ekpoma, Edo State, Nigeria and Department of Haematology, Irrua Specialist Teaching Hospital, Irrua, Edo State, Nigeria 2 Department of Microbiology, Faculty of Life Sciences, Ambrose Alli University, Ekpoma, Edo State, Nigeria Abstract The CD3 protein complex is an important T cell marker. This study aimed at determining the CD3 T lymphocytes count of apparently healthy adult subjects in Ekpoma, Nigeria. A total of two hundred and sixty (260) apparently healthy subjects were randomly recruited for the study. The subjects were of the both sexes and belonged to 17 to 50 years of age range. Five millitres (5ml) of whole blood was collected from the antecubital vein and dispensed into Ethylene Diamine Tetraacetic Acid (EDTA) bottles. Flow cytometry was used to determine the absolute counts (cells/ȝl) of CD3+ T lymphocytes. The mean CD3 absolute count of the male subjects is 1445.88 cells/ȝl (Median 1460.00 cells/ȝl, Range 783.38-2222.70 cells/ȝl) compared to a mean CD3 absolute count of the female subjects – 1720.27 cells/ȝl (Median 1741.00 cells/ȝl, Range 686.20 – 2145 cells/ȝl). There is a significant higher difference (P<0.05) in the mean CD3 count of the female subjects compared to males. The overall (total) mean CD3 absolute count of the subjects studied was 1483.08 ± 381.55 cells/ȝl (Median 160.00 cells/ȝl, Range 788.73 – 2159.00 cells/ȝl). The age groups of 17-24 years, 25-32 years and 33-40 years showed a statistical significant difference (P<0.05) when the mean CD3 absolute counts of the female subjects were compared to males. However, the age group of 40 and above did not reveal any significant difference when both means were compared. In conclusion, the study has revealed that the mean CD3+ T lymphocyte count obtained in our study population is unique to the study and different from those of other populations and this will guide the management of immune-related disorders. Keywords: CD3 count, Reference ranges, Apparently healthy adults, Ekpoma. 1. Introduction The Cluster of Differentiation (CD) used in lymphocyte nomenclature, is a protein expressed on the cells of haemopoietic system. Cells with different functions express different CD molecules. For instance, CD3 cells are total T lymphocytes, while CD4 cells are T-helper cells and over 300 molecules have so far been reported (WHO, 2007). Cluster of differentiation 3 (CD3) is a multimeric protein complex, known historically as the T3 complex, and is composed of four distinct polypeptide chains that assemble and function as three pairs of dimers. The CD3 complex serves as a T cell co-receptor that associates non-covalently with the T cell receptor (TCR) (Smith- Garvin et al., 2009). The CD3 protein complex is a defining feature of the T cell lineage, therefore anti-CD3 antibodies can be used effectively as T cell markers (Chetty & Gatter, 1994). The CD3 protein complex is an important T cell marker for the classification of malignant lymphomas and leukaemias (T cell neoplasms). The effector, memory and immunoregulatory roles of CD3 T lymphocytes (CD3 T cells) have been variously described especially in this era of unfortunate HIV/AIDS challenge (Klose et al., 2007). It has also been established for years that CD3 T cells play critical roles in the functioning of B cells and effective responses of CD8 T cells. Moreover, the role of CD3 T cells in cancer immunotherapy and in the control of auto-immunity is gaining increased attention (Idigbe et al., 2010). CD3 can also be used for the identification of T cells in coeliac disease (Leon, 2011), lymphocytic colitis and collagen colitis (Mosnier et al., 1996; Sapp et al., 2002). Full understanding of the values of CD3 T cells in African populations are not fully understood with both relatively high and low values being reported in various countries (Kalinkovich et al., 1998; Bussman et al., 2004., Klose et al., 2007). There is paucity of published data on CD3 T cells of Nigerians and even in Ekpoma inhabitants. The only data available are on CD4 T cells in Nigeria, and most of the studies were on immunocompromised populations (Nwokedi et al., 2007; Forbi & Agwale, 2009; Forbi et al., 2010). Therefore, there might be variation in the CD3 T lymphocytes count from one population to another and even in the instruments used for the enumeration (WHO, 2007). The aim of the present study is to determine the values of CD3 T cells among apparently healthy individuals residing in the semi-urban population of Ekpoma, Nigeria. 2. Materials and Methods This study was carried out in Ekpoma, the administrative headquarters of Esan West Local Government Area of Edo State, Nigeria. Ekpoma is the fourth largest town in Edo State and lies between latitude 6 0 43'N and 6 0 45’N of the Equator and longitude 6 0 6'E to 6 0 8'E of the Greenwich Meridian with a population of 170,123 people 65 www.ijrp.org IJRP 2022, 99(1), 65-70; doi:.10.47119/IJRP100991420223073