Drug injection device with particular optical window elements for unambiguous legibility of dose value

An arrangement comprising an optical element and an indication member for a drug delivery device is provided. The indication member comprises a plurality of indicia. The optical element comprises an imaging section and a light-transmissive non-imaging section, wherein the indication member is movable with respect to the optical element such that the indicia can be successively moved into a display position relative to the optical element. The imaging section is configured such that, when a first indicium is arranged in the display position, the first indicium is imaged by the imaging section into an imaging solid angle. The non-imaging section is configured such that light defining a second indicium is deflected by the non-imaging section such that the second indicium cannot be identified by a user in the imaging solid angle on a viewing side of the optical element.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. National Phase application pursuant to 35 U.S.C. § 371 of International Application No. PCT/EP2014/054527 filed Mar. 10, 2014, which claims priority to European Patent Application No. 13159049.9 filed Mar. 13, 2013. The entire disclosure contents of these applications are herewith incorporated by reference into the present application.

FIELD OF INVENTION

Arrangement for a Drug Delivery Device

The present disclosure relates to an arrangement for a drug delivery device, e.g. an injector-type device, such as a pen-type injector. Furthermore, the present disclosure relates to a drug delivery device.

BACKGROUND

For example, a drug delivery device is known from WO 2008/058665 A1.

It is an object of the present disclosure to facilitate identification of indicia of a drug delivery device.

This object is achieved by the subject-matter of the independent claim. Advantageous embodiments and refinements are subject-matter of the dependent claims.

SUMMARY

One aspect of the present disclosure relates to an arrangement for a drug delivery device, such as an injector-type device. The arrangement comprises an optical element and an indication member for a drug delivery device. The indication member comprises a plurality of indicia. The optical element comprises an imaging section and a non-imaging section. The indication member is movable with respect to the optical element such that the indicia can be successively moved into a display position relative to the optical element.

In an embodiment, the imaging section is configured such that, when the first indicium is arranged in the display position, the first indicium is imaged by the imaging section into an imaging solid angle.

The viewing side of the optical element may be a side of the optical element which faces away from the indication member. Thereby, the indication member may be arranged on a side of the optical element which is opposite to the viewing side.

In an embodiment, the non-imaging section is configured such that light defining the second indicium, e.g. light reflected from the indication member, is deflected by the non-imaging section such that the second indicium cannot be identified by a user in the imaging solid angle on the viewing side of the optical element. Expediently, the imaging section is transparent.

In an embodiment, the non-imaging section is light-transmissive.

A further aspect of the present disclosure relates to a drug delivery device comprising the arrangement, wherein the optical element is designed to form a dose window of the drug delivery device. The dose window may, e.g., be provisioned to allow the user to view or inspect dose indicia of the drug delivery device which may be provided on an inner part of the drug delivery device such as the indication member. The distance between the indication member and the optical element may span a range between about 0.2 millimeter, e.g. in a central region of the optical element, and 0.3 millimeter, e.g. in a peripheral region of the optical element. The indication member may be a display member of the drug delivery device. The drug delivery device may comprise a needle or a needle assembly through or via which a drug may be dispensed from the drug delivery device.

In an embodiment, the arrangement is configured such that during a dose set and/or a dose dispense operation of the drug delivery device, different indicia can be moved into the display position. Thereby, the indication member may be moved with respect to the optical element or vice versa.

Light, particularly visible light, defining indicia may mean that, said light defines a contour of the indicia. Thereby, the indicia itself and the region surrounding the indicia may reflect the light differently such that said contour becomes visible. Consequently, the light may either be reflected from the indicia or from the region surrounding the indicia.

Preferably, the display position of an indicium is a position in which a dose or a size of a dose of the drug delivery device corresponding to this indicium is set and wherein the user can positively identify said indicium through the optical element in the imaging solid angle.

The imaging solid angle is a solid angle in which the indicium, which is arranged in the display position, can be positively identified by the user. An image which is generated by the imaging section may thereby be defined or confined by the imaging solid angle, wherein the imaging solid angle extends over the image. Said image may relate to the first indicium when the first indicium is arranged in the display position.

From a manufacturing point of view, it may be expedient to form a housing of the drug delivery device and the dose window from a single component. This means that the housing would be transparent and requires an opaque covering. To this effect, a printing or over-labeling of the housing would usually leave a gap around the dose window. When a certain dose is set by the drug delivery device and an indicium corresponding to this dose is indicated through the dose window, it is possible that markings, characters or another indicium which is not arranged in the display position is visible through the gap. This may cause confusion to the user when a dose is set. If the dose window is configured as a magnifying lens, said markings or indicia may appear misaligned and in this way cause considerable confusion to the user.

With the present disclosure, it is achieved that, when the first indicium is arranged in the display position, the first indicium is visible for the user while the second indicium which may be arranged adjacent to the first indicium cannot be identified by the user. In this way, confusion of the user is prevented, as the second indicium—which may be arranged adjacent to the first indicium or any other markings—cannot be identified by the user in the imaging solid angle on a viewing side of the optical element.

In an embodiment, the indicia comprise numbers, such as dose numbers and/or non-numerical characters, wherein the non-numerical characters preferably

separate adjacent numbers. The non-numerical characters may comprise symbols, such as dashes.

Preferably, the first indicium comprises a dose number and the second indicium which may be adjacent to the first indicium comprises a dash, separating the first indicium from a further indicium. Alternatively, the first and the second indicium may both exhibit dose numbers, indicating subsequent sizes of set doses or quantities of drug to be dispensed from the drug delivery device. Subsequent sizes may differ from each other by, e.g. two units, four units, or just one unit. A unit may relate to a minimum amount of drug which may be set to be dispensed by the drug delivery device. The indicia may, e.g. be printed, on the outer surface of the indication member.

In an embodiment, the non-imaging section surrounds the imaging section, particularly, as seen in plane view from the viewing side. The non-imaging section may define a boundary area of the optical element. As an advantage, it is easily achieved independent from the mutual arrangement of the first indicium and the second indicium that the first indicium is imaged by the imaging section while the second indicium cannot be identified by the user in the imaging solid angle on a viewing side of the optical element, provided that the first indicium is arranged in the display position.

In an embodiment, the optical element is comprised by a body and the arrangement comprises a covering which defines a window, wherein the window is arranged and configured such that the optical element is visible through the window. Preferably, the covering covers the body in a region different from the region where the optical element is situated. Apart from the optical element, the body may be opaque or translucent or partly opaque or translucent. Alternatively, the body may be transparent. Preferably, the body is transparent.

In a preferred embodiment, the covering is opaque. This is particularly expedient, if the body is embodied transparent such that the covering can define the window. Thereby, it is achieved that a user can see through the window or, as the case may be the optical element while structures which are not covered by the window are not visible to the user or blanked. As an advantage, the attention of the user may be focussed to structures or elements, as. e.g. indicia which are made visible through the window and/or the optical element, e.g. from the outside of the drug delivery device.

In the present disclosure, “transparent” may relate to the property of structures through which objects—including its contours—may be viewed or resolved by a user or an observer. “Translucent” may relate to the property of structures which are partly light-transmissive, such that contours of objects may not be viewed or resolved.

The body may constitute an outer housing of the drug delivery device. Preferably, the user cannot identify any features of the drug delivery device which are not covered by the window.

In an embodiment, the imaging section extends over the first indicium when the first indicium is arranged in the display position.

In an embodiment, the non-imaging section at least partly extends over the second indicium when the first indicium is arranged in the display position. In other words, the projection of the imaging section on the indication member extends over the first indicium when the first indicium is arranged in the display position and the projection of the non-imaging section at least partly extends over the second indicium when the first indicium is arranged in the display position. Thus, the projection of the optical element on the indication member may extend over the first indicium and partly also over the second indicium or any further indicium which may be arranged adjacent to the first indicium.

In an embodiment, the imaging section is elevated as compared to the non-imaging section. This embodiment may advantageously enable the embodiment of the imaging section according to specific imaging requirements of the imaging section. For example, the elevation of the imaging section facilitates an embodiment of the imaging section as or in accordance with a magnifying element. Additionally, a side wall of the imaging section which may be present due to the elevation may reflect light which defines the second indicium. Thereby, the elevation may facilitate that said light is deflected such that the light cannot be identified by the user in the imaging solid angle.

In an embodiment, the imaging section is formed in accordance with a magnifying element, such as a lens. As an advantage of this embodiment, readability of indicia may be improved, especially for persons with poor eyesight, as for instance elderly persons. Also, said embodiment may be advantageous for diabetics which often suffer from poor eyesight.

When the imaging section is embodied as a magnifying element, the user may view the first indicium magnified in the viewing solid angle when the first indicium is arranged in the display position.

In an embodiment, the non-imaging section is a transparent refractive section which comprises a boundary surface. The boundary surface is arranged and configured such that, when the first indicium is arranged in the display position, the second indicium cannot be identified by the user in the imaging solid angle on the viewing side of the optical element.

In an embodiment, the boundary surface comprises a plane or an even portion which is obliquely oriented with respect to an optical axis of the arrangement.

In the present disclosure, “oblique” or “obliquely” preferably means that a component is not arranged or oriented perpendicularly with respect to another component.

The optical axis may be an axis along which the optical element and the first indicium are aligned when the first indicium is arranged in the display position.

Due to the oblique orientation of the boundary surface of the non-imaging section, light emitted or reflected from the indication member and passing through the optical element may be refracted differently from the non-imaging section, as compared to the imaging section, such that light defining the second indicium and which passes through the non-imaging section is deflected in an area outside of the viewing solid angle.

In an embodiment, the boundary surface comprises a structured surface which is configured such that, when the first indicium is arranged in the display position, there is a first solid angle outside of the imaging solid angle on a viewing side of the optical element into which the second indicium is imaged by the structured surface, wherein the second indicium cannot be identified by the user in a second solid angle on the viewing side which is arranged outside of the imaging solid angle and which is different from the first solid angle.

Preferably, the non-imaging section is configured such that the boundary surface surrounds the imaging section. The structured surface may comprise a plurality of planes or even portions, the surface normals of which are inclined with respect to each other and/or with respect to the optical axis. On the viewing side of the optical element, one or more surface normals of the portions are preferably directed away from the optical axis such that light emitted or reflected from the indication member and defining a second indicium while the first indicium is in the display position, is deflected by the boundary surface such that the second indicium cannot be identified by the user in the imaging solid angle on the viewing side of the optical element. In other words, the boundary surface may deflect light defining the second indicium out of the viewing solid angle. Thus, only the first indicium can be identified by the user in the imaging solid angle.

The even portions may be suitable to image, e.g. the second indicium, when the first indicium, being arranged adjacent to the second indicium, is in the display position. Advantageously, the user is not confused by the second indicium or further indicia or markings when reading or inspecting the set dose or the size of the set dose of the drug delivery device in a solid angle outside of the viewing solid angle.

In an embodiment, the non-imaging section is a translucent diffusive section. According to this embodiment, it can advantageously be achieved that, when the first indicium is arranged in the display position, the first indicium is imaged by the imaging section into the imaging solid angle and that the second indicium cannot be identified by the user, as it is not imaged but diffused by the non-imaging section. The translucent diffusive section may comprise a roughened surface which prevents an imaging of the second indicium when the first indicium is arranged in the display position. Said roughened surface may comprise a surface texture with features having dimensions on the micrometer scale, e.g. one or more micrometers up to 1 millimeter, such that light emitted or reflected from the indication member and passing through the non-imaging section, is diffused.

In an embodiment, the non-imaging section is provided along opposite sides of the optical element. Said opposite sides may face a proximal and/or a distal end of the arrangement. This is particularly expedient, when, e.g. a dash separating two dose numbers is also arranged accordingly on the indication member, i.e. at sides of the first indicium which face the proximal and/or to the distal end of the arrangement, when the first indicium is arranged in the display position. On the remaining sides of the optical element, a non-imaging section may not be required, as at the corresponding sides of the first indicium on the indication member, there may be no indicium provided which could be imaged in the imaging solid angle.

A longitudinal axis of the arrangement may extend from the distal to the proximal end of the arrangement. The longitudinal axis of the arrangement may coincide with the longitudinal axis of the drug delivery device. The distal end of the arrangement may be or face towards a distal end of the drug delivery device and the proximal end of the arrangement may be or face towards a proximal end of the drug delivery device.

The distal end of the drug delivery device may refer to an end at which drug may be dispensed from the drug delivery device and/or at which the needle may be arranged.

The proximal end of the drug delivery device may refer to an end at which is arranged furthest away from where drug may be dispensed from the drug delivery device and/or furthest away from the needle.

DETAILED DESCRIPTION

Like elements, elements of the same kind and identically acting elements may be provided with the same reference numerals in the figures. Additionally, the figures may be not true to scale. Rather, certain features may be depicted in an exaggerated fashion for better illustration of important principles.

FIG. 1shows a schematic illustration of a drug delivery device200. The drug delivery device200may be an injector-type device, such as a pen-type injector. The device may be operable such that fixed or variable doses, preferably doses of a user settable size, of drug may be set and dispensed by a user. The drug delivery device200comprises a body6and a covering19(cf.FIG. 2) defining a window8. The covering19may be opaque. Through the window8the actually set dose is preferably visible for the user. The body6further comprises an optical element1having a rectangular-like shape as seen in plan view. The optical element1is designed to form a dose window of the drug delivery device200in which dose information, as e.g. the size of a set dose, is displayed to the user. The optical element1is visible within the window8. The covering19may cover the body6in a region different from the region where the optical element1is situated. The optical element1comprises an imaging section4and a non-imaging section5. The imaging section4is preferably transparent to visible light. The non-imaging section5is preferably transmissive to visible light. The non-imaging section5surrounds the imaging section4. The optical element1is framed by the window8. Preferably, the arrangement is thereby fixed to the body6. The drug delivery device200further comprises an indication member2which is provided with a plurality of indicia, particularly dose numbers3. The indication member2which is arranged inside the body6may form a display member of the drug delivery device. In the described situation, a dose number3is arranged in a display position relative to the optical element1. In this situation, the dose number3is imaged by the imaging section4into an imaging solid angle9. The imaging solid angle9exhibits a solid angle in which the indicium3can be easily and positively inspected or viewed by the user of the drug delivery device200from a viewing side of the optical element1. The viewing side (cf.13inFIG. 2) of the optical element1is a side of the optical element1which faces away from the indication member2. The viewing side13is on the outside of the drug delivery device200.

The indicium3may indicate the size of a set dose of the drug delivery device200, e.g. the number of units of drug which are set to be dispensed. The indication member2comprising the dose numbers3may be movable with respect to the optical element1during a dose setting and/or a dose dispensing operation of the drug delivery device200such that an dose number adjacent to the depicted dose number3is moved into the display position. The mentioned movement may be an axial or a helical movement of the optical element1or a rotation around a longitudinal axis x of the drug delivery device200. Accordingly, the dose numbers may be arranged or aligned axially, helically or angularly around an outer circumference of the indication member2(cf.FIG. 3). The longitudinal axis of the drug delivery device200may extend between a distal end and a proximal end of the drug delivery device200.

FIG. 2shows the arrangement100comprising the optical element1in a schematic section. The drug delivery device200may comprise the arrangement100. The optical element1comprises the imaging section4and the non-imaging section5. Due to the sectional illustration inFIG. 2, the imaging section4appears to be arranged between two portions of the non-imaging section5. The longitudinal axis x of the drug delivery device200may coincide with a longitudinal axis of the arrangement100. The indication member2is provided with a plurality of indicia which are represented in this embodiment, but not limited thereto by a first dose number3aand with a second dose number3band3c. Further indicia are represented here by dashes7which are arranged adjacent to the dose numbers3a,3band3c. The direction along which the dose numbers3a,3band3care aligned (horizontal direction) may be parallel to the longitudinal axis x. The dose number3awhich may represent a first indicium faces the imaging section4of the optical element1. In the situation depicted inFIG. 2, the first indicium3ais arranged in the display position relative to the optical element1and can thus be identified by the user in the imaging solid angle9. An optical axis11is indicated inFIG. 2which may run through a center of the imaging section4. The optical axis11may further run radially with respect to the longitudinal axis x. The imaging section4or a projection of the imaging section4on the indication member2extends along the dose number3a. The optical element1extends along the dose number3a, the dashes7and partly along the dose numbers3band3c. The distance between the indication member2and the optical element1may span a range between about 0.2 millimeter and 0.3 millimeter.

The oblique dashed lines on each side of the arrangement100inFIG. 2indicate the imaging solid angle9. The imaging section4of the optical element1is elevated as compared to the non-imaging section5. As an advantage of this elevation, the imaging section4may be configured, e.g. according to a magnifying lens, as indicated by the curved surface of the imaging section4. Accordingly, the dose number3amay be magnified to the user, when the user reads or identifies the dose number3a.

The imaging section4is configured such that the dose number3ais imaged by the imaging section4into the imaging solid angle9. The non-imaging section5is configured such that light defining the dose numbers3band3cand/or the dashes7, i.e. elements on the indication member which are not in the display position, is deflected by the non-imaging section5such that said elements cannot be identified by the user in the imaging solid angle9on the viewing side13of the optical element1. The arrangement100may be configured such that when the size of a dose of drug which may be indicated by the dose number3a—and which is imaged by the imaging section4—is varied by the user, the indication member2may be moved such that the dose number3ais moved out of the display position. Consequently, one of the dose numbers3band3cis moved into the display position. Thus, this indicium will then be imaged by the imaging section into the imaging solid angle9.

FIG. 3shows a partial simplified top view of the indication member2comprising exemplary dose numbers3and dashes7. The dose number3and the dashes7which separate the indicia3are aligned along an axis parallel to the longitudinal axis x, respectively. The indicia3are arranged helically, whereby two vertically or circumferentially consecutive indicia indicate a difference of two dose units. InFIG. 3, only a fraction of possible indicia is indicated schematically.

FIG. 4shows a partial schematic section of the arrangement100, wherein the dose number3ais in the display position comparable to the situation shown inFIG. 2. The imaging section4is again elevated as compared to the non-imaging section5. The imaging section4is preferably formed according to a magnifying lens. A side wall26of the imaging section runs between the imaging section4and the non-imaging section5. The side wall26connects the imaging section4and the non-imaging section5. The side wall26may define by how much the imaging section4is elevated over the non-imaging section5. The dose number3ais imaged by the imaging section4into the imaging solid angle9, as is indicated by the optical path19such that the user can identify the dose number3ain the imaging solid angle9on a viewing side13of the optical element1. In this embodiment, the non-imaging section5is preferably transparent to visible light and comprises a boundary surface10. The boundary surface10may be oriented obliquely with respect to the optical axis11. The boundary surface10may be partially even or comprise a plane or portions16, e.g. at each of the optical element1, when the optical element1is rectangular. The portions16may be even and define surface normals14which are inclined with respect to the optical axis11. Due to the inclination of the boundary surface10, light defining the dose numbers3band3cis deflected out of the imaging solid angle9such that the user cannot identify said dose numbers in the imaging solid angle9. Although not explicitly indicated, the portions may also be uneven in section. Exemplary optical paths20aand20bof light defining the dose number3cand extending from the indication member2, are shown inFIG. 4. Light according to the optical path20apasses through the non-imaging section5. The light is deflected by the non-imaging section5towards an area outside of the viewing solid angle9such that the dose numbers3ccannot be identified in the viewing solid angle9. The light is thereby refracted and subsequently reflected, at the side wall26in a longitudinal direction such that it is deflected away from the optical axis11. Additionally or alternatively, light running according to the optical path20bmay re-enter into the imaging section of the optical element1after having passed the non-imaging section5. Then, the light may also be reflected, as e.g. totally reflected at a surface27of the imaging section4such that it does not leave the optical element1within the imaging solid angle9.

On the other hand, light according to an optical path21originating from the viewing side13is refracted by the non-imaging section5and passes through the same. When the light subsequently exits the non-imaging section5, it may be deflected again such that it does not meet the dose numbers3band3c. In other words, the light is deflected by the non-imaging section5due to the inclination of the boundary surface10such that only the dose number3acan be viewed by the user, although the optical element1extends in parts also over the dose numbers3band3c. The index of refraction of the non-imaging section5may be adjusted accordingly. Due to the inclination of the boundary surface10of the non-imaging section5of the optical element1, the dose numbers3band3ccannot be identified by the user in the imaging solid angle9on the viewing side13of the optical element1. Outside of the imaging solid angle9on the viewing side13of the optical element1, at least fractions of the dose numbers3band3cmay be identified by the user, as light defining the second indicia may be deflected accordingly by the boundary surface10. Although not explicitly indicated, the optical element may also be configured such that the non-imaging section extends only partly along a circumference of the optical element. For example, the non-imaging section may extend, only along sides of the optical element which face a proximal and/or a distal end of the arrangement (cf. inFIG. 5). On the remaining sides of the optical element, a non-imaging section may not be required, as at the corresponding sides of the first indicium on the indication member, there may be no second indicium, provided which could be imaged in the imaging solid angle. InFIG. 4, the dashes7separating the dose numbers are omitted. However, the dose numbers3band3cmay also be embodied as dashes. Nevertheless, it is advantageous that the non-imaging section5extends about the whole circumference of the imaging section4.

FIG. 5shows a partial perspective view of the arrangement100by means of a further exemplary embodiment. As described in connection withFIG. 4, the optical element1comprising the imaging section4and the non-imaging section5is preferably transparent to visible light. It is shown inFIG. 5that the non-imaging section5only extends along a side18of the optical element1which faces a proximal and/or a distal end of the arrangement100. Accordingly, indicia (not indicated) may in this embodiment also be arranged along the longitudinal axis x. Although not explicitly indicated, the optical element1may also be configured such that the non-imaging section5surrounds the imaging section4. The non-imaging section5may comprise a boundary surface10with a plurality of portions16. Each portion16may be even or a plane. The portions16may form a structured surface17of the boundary surface10. In this case, surface normals of the portions16may be inclined with respect to the optical axis11and/or with respect to one another. Although not explicitly indicated, the portions16may also be uneven or curved. Preferably, the portions16are configured such that light emitted or reflected from the indication member2and passing through the non-imaging section5, is deflected into a direction which is transverse to the longitudinal axis x. Preferably, the portions17image, e.g. the second indicium into a first solid angle (cf.24inFIG. 6) outside of the viewing solid angle9, when the first indicium is in the display position. As an advantage of this embodiment, there may be second solid angles (cf.25inFIG. 6) outside of the imaging solid angle9from which the second indicia cannot be identified by the user such that the user is not confused, e.g. during the inspection of the size of the set dose.

FIG. 6shows a schematic transverse section of the arrangement100of the embodiment shown inFIG. 5, wherein the dose number3ais arranged in the display position. The arrangement100is shown curved. This curvature may be determined by the curvature of the drug delivery device200. InFIG. 6, a cross-section of the non-imaging section5fromFIG. 5is shown. The non-imaging section5comprises three equilateral cuts defining portions16(cf. portions16inFIG. 5). When light emitted or reflected from the indication member2passes through the non-imaging section5, it is formed by the portions16such that a user cannot identify dose numbers3b,3cand3dmay represent a second indicium, respectively. Said dose numbers are preferably arranged adjacent to the dose number3a(not shown) representing a first indicium. In contrast to the embodiments shown in theFIGS. 2 and 4, the dose numbers3b,3cand3dare not aligned longitudinally but along an outer circumference of the indication member2. Exemplary optical paths22and23are shown which indicate that the light emitted or reflected from the indication member2is deflected by the portions16out of the viewing solid angle9. Thereby, light according to the optical path22undergoes a reflection, as e.g. a total reflection and then exits from the non-imaging section5, while light according to the optical path23is simply refracted by the non-imaging section5.

Regions on the indication member2in which the dose numbers3b,3cand3dare arranged may not be met by light passing through the non-imaging section5from the viewing side13, as the light is deflected away from said regions due to the portions16of the non-imaging section5. The regions are schematically defined by means of the dashed lines28next to the indicia3b,3cand3d. The index of refraction of the non-imaging section5may be adjusted accordingly. Due to the configuration of the structured surface17, the dose numbers3b,3cand3dcannot be identified by the user in the imaging solid angle9on the viewing side13of the optical element1.

In a further exemplary embodiment, the non-imaging section (cf.FIG. 2) is a translucent diffusive section. To this effect, the non-imaging section may comprise a roughened surface which prevents an imaging of an indicium being arranged adjacent to the first indicium, when the first indicium is arranged in the display position. Said roughened surface may comprises a surface texture with features having dimensions on the micrometer scale, e.g. one or more micrometers up to 1 millimeter, such that light emitted or reflected from the indication member and passing through the non-imaging section, is diffused.

The term “drug”, as used herein, preferably means a pharmaceutical formulation containing at least one pharmaceutically active compound,

or an Exendin-4 derivative of the sequence

There are five types of mammalian Ig heavy chain denoted by α, δ, ϵ, γ, and μ. The type of heavy chain present defines the isotype of antibody; these chains are found in IgA, IgD, IgE, IgG, and IgM antibodies, respectively.

The scope of protection is not limited to the examples given herein above. The invention is embodied in each novel characteristic and each combination of characteristics, which particularly includes every combination of any features which are stated in the claims, even if this feature or this combination of features is not explicitly stated in the claims or in the examples.