IMMUNOLOGY

Detailed explanation-1: -Memory cells persist after a primary exposure to a pathogen. If re-exposure occurs, memory cells differentiate into effector cells without input from the innate immune system.

Detailed explanation-2: -Memory B cells can survive for decades, which gives them the capacity to respond to multiple exposures to the same antigen. The long-lasting survival is hypothesized to be a result of certain anti-apoptosis genes that are more highly expressed in memory B cells than other subsets of B cells.

Detailed explanation-3: -Instead, memory B cells are defined as long-lived and quiescent cells that are poised to quickly respond to antigen upon recall (2–5). Both memory B cells and antibody-secreting cells (ASCs) are the product of antigen activation and, most often, interaction with cognate T helper cells.

Detailed explanation-4: -The adaptive, or acquired, immune response takes days or even weeks to become established-much longer than the innate response; however, adaptive immunity is more specific to an invading pathogen. This part of the immune system works in tandem with the innate immune response to neutralize pathogens.

Detailed explanation-5: -Types and functions of lymphocytes Most lymphocytes are short-lived, with an average life span of a week to a few months, but a few live for years, providing a pool of long-lived T and B cells.