CD4 and mastitis: These include CD4+ T cell depletion and immunological non-response in Human Immunodeficiency Virus (HIV) infection, the development of Human Papillomavirus (HPV)-associated cervical cancer, Staphylococcus aureus-induced endometritis and mastitis, as well as male infertility, pre-eclampsia, and ovarian cancer linked to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection.