CD4 and systemic inflammatory response syndrome: Otherwise, lymphocytes, in their variety (B cells; T cells CD4-positive, CD4/CD8-negative or CD8-positive; natural killer T cells), are especially responsible for adaptive immunity, providing an antigen-specific response regulated by the major histocompatibility complex (MHC) class I. Lymphocyte activity is involved in host response to viruses, tumor cells, atopy and in SIRS too [14].