Changes

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The first immunoglobulin produced during an immune response is '''always [[IgM]]''' because the Cμ gene is the first constant H chain gene downstream of the variable domain. After antigenic exposure the [[IgM]]+ B-cells differentiate and begin to synthesise other classes of immunoglobulin, but only under the '''direct influence of a T-cell'''. This system is known as '''immunoglobulin heavy chain switching'''. The [[IgG]] antibodies produced in both primary and secondary responses originate from the same clones of B-cells as the [[IgM]] antibodies. The different antibody classes have the same variable domain combinations, and therefore the same antigenic specificity. Under the influence of T-cells, B-cells undergo immunoglobulin heavy chain switching and the B-cells mature from [[IgM]] to [[IgG]] producers and IgE and IgA producers can also be generated. These immunoglobulins tend to be produced within lymphoid tissue associated with mucosal surfaces.

The first immunoglobulin produced during an immune response is '''always [[IgM]]''' because the Cμ gene is the first constant H chain gene downstream of the variable domain. After antigenic exposure the [[IgM]]⁺ B-cells differentiate and begin to synthesise other classes of immunoglobulin, but only under the '''direct influence of a T-cell'''. This system is known as '''immunoglobulin heavy chain switching'''. The [[IgG]] antibodies produced in both primary and secondary responses originate from the same clones of B-cells as the [[IgM]] antibodies. The different antibody classes have the same variable domain combinations, and therefore the same antigenic specificity. Under the influence of T-cells, B-cells undergo immunoglobulin heavy chain switching and the B-cells mature from [[IgM]] to [[IgG]] producers, with [[IgE]] and [[IgA]] producers generated under certain immune responses. These immunoglobulins (IgA and IgE) tend to be produced within lymphoid tissue associated with mucosal surfaces.

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