1

                                                                    EXHIBIT 10.8

              SECOND AMENDMENT TO DEVELOPMENT AND SUPPLY AGREEMENT

     This Second Amendment to Development and Supply Agreement ("Amendment"),
effective as of June 12, 2000, is made by and between Luminex Corporation, a
Delaware corporation ("LUMINEX"), and Bio-Rad Laboratories, Inc., a Delaware
corporation ("BIO-RAD") (LUMINEX and BIO-RAD collectively, the "Parties"), and
amends that certain Development and Supply Agreement dated as of March 19, 1999
between the Parties (as previously amended by amendment dated January 13, 2000,
the "Agreement").

     The Parties hereby agree as follows, for the purpose of amending the
Agreement in the following respects:

1.   Amendments. The Parties hereby agree to amend the Agreement in the
     following respects:

     1.1  Magnetic Bead Amendments.

          1.1.1 Section 2.1(d) of the Agreement is hereby amended to delete all
sentences in that section except the first two sentences and add the following
as the third and fourth sentences of such section:

          "Exhibit F sets forth the criteria for BIO-RAD's supply of Magnetic
          Beads to LUMINEX and LUMINEX's treatment of such Magnetic Beads. The
          tolling fees payable by BIO-RAD to LUMINEX with respect to Magnetic
          Beads shall be the prices set forth in Exhibit G (the "Magnetic Bead
          Prices")."

          1.1.2 Section 2.2 of the Agreement is hereby amended to delete the
phrase in the last sentence "or the Development Agreement."

          1.1.3 Sections 1.4, 4.2, 4.3, 4.4, 4.5, 4.8, 4.10, 4.15, 4.16 and
Article 7 of the Agreement are hereby amended to delete all instances of the
word "Standard" when preceding the word "Beads."

          1.1.4 Section 4.6(b) of the Agreement is hereby amended to delete the
last sentence of such section and replace it with the following:

          "The amounts of the tolling fees for Magnetic Beads shall be as set
          forth in Exhibit G. These Magnetic Bead Prices will be effective
          during the first [**] of this Agreement, after which time LUMINEX may,
          [**]. Such increases may occur no more frequently than [**]. Each [**]
          increase during the [**]."

          1.1.5 Section 4.9 of the Agreement is hereby amended to add the phrase
", Magnetic Bead Prices" following the phrase "Payment of the Unit Transfer
Fee."

          1.1.6 Exhibits F and G attached to this Amendment are hereby added as
Exhibits to the Agreement.

- ----------

[**] Indicates that material has been omitted and confidential treatment
requested therefor. All such material has been filed separately with the
Commission pursuant to Rule 24b-2.



   2


     1.2  Standard Bead Pricing Amendments.

          1.2.1 The first sentence of Section 4.6(a) of the Agreement is hereby
                amended by deleting the phrase "[**] for ever [**] units of
                Standard Beads purchased, where a "unit" of Standard Beads is
                equal to one microsphere bead ("Unit Transfer Fee") and
                substituting therefor:

          "for Beads purchased hereunder according to the prices set forth on
          Exhibit H, as amended ("Unit Transfer Fees")."

          1.2.2 All references in the Agreement to "Unit Transfer Fee" are
hereby amended to be references to "Unit Transfer Fees."

          1.2.3 Exhibit H, attached to this Amendment, is hereby added as an
Exhibit to the Agreement.

          1.2.4 Exhibit I, [**], rev. C, attached to this Amendment, is hereby
added as an Exhibit to the Agreement.

          1.2.5 The end of the first sentence of Section 9.1 is hereby amended
to add the phrase ", and Beads for BIO-RAD's [**] shall be [**]."

     1.3  Luminex 100 System Pricing Amendments.

          1.3.1 Exhibit E to the Agreement is hereby amended by deleting such
Exhibit in its entirety and substituting therefor Exhibit E attached to this
Amendment.

          1.3.2 Exhibit J, "[**], attached to this Amendment, is hereby added as
an Exhibit to the Agreement.

     1.4  Warranty Amendments.

          1.4.1 Section 6.1 of the Agreement is hereby amended by adding the
following to the end of such Section:

          [**]

          1.4.2 In Exhibit C of the Agreement, the first sentence of the
paragraph "Limited Warranty" is hereby amended by deleting the phrase "one year
from delivery to an End User, but no more than fifteen (15) months from delivery
to BIO-RAD" and substituting therefor:

          [**]

     1.5  Defined Terms Amendments.

- ----------

[**] Indicates that material has been omitted and confidential treatment
requested therefor. All such material has been filed separately with the
Commission pursuant to Rule 24b-2.



   3


          1.5.1 Section 1.5 is hereby amended by deleting such Section in its
entirety.

          1.5.2 Section 1.11 is hereby amended by deleting such Section in its
entirety and substituting therefor the following

          "Luminex Systems" means the following laser based fluorescent
analytical test systems:

                                               Luminex Part Number

          Standard Luminex 100                        [**]
          [**]                                        [**]
          [**]                                        [**]
          Luminex Sheath Delivery System              CNS001-01
          Luminex XY Platform                         CNX002-01

          * Defined further below

          [**] (for BIO-RAD's Life Sciences Group):

          [**]

          [**] (for BIO-RAD's Clinical Diagnostics Division):

          [**]

          1.5.3 All references in the Agreement to "Bio-Rad System" or
"Luminex100 System" are hereby amended to be references to "Luminex Systems."

          1.5.4 All references in the Agreement to "Luminex100 Purchase Price"
(including the definition of such term) are hereby amended to be references to
"System Purchase Price."

2.   Effect of Amendment.

     2.1 This Amendment amends the Agreement to incorporate the terms and
conditions set forth in this Amendment. The relationship of the Parties shall
continue to be governed by the terms and conditions of the Agreement, as amended
herein; and in the event that there is any conflict between the terms and
conditions of the Agreement and this Amendment, the terms and conditions of this
Amendment shall control.

     2.2 As used in this Amendment, all capitalized terms shall have the
meanings defined for such terms in this Amendment or, if not defined in the
Amendment, the meanings defined in the Agreement.

     2.3 This Amendment (including the Exhibits hereto) constitute the entire
agreement between the Parties in connection with the subject matter hereof and
supersede all prior and contemporaneous

- ----------

[**] Indicates that material has been omitted and confidential treatment
requested therefor. All such material has been filed separately with the
Commission pursuant to Rule 24b-2.


   4

agreements, understandings, negotiations and discussions, whether oral or
written, of the Parties with respect to such subject matter.

         IN WITNESS WHEREOF, the Parties have executed this Amendment to be
effective as of the date first written above.

LUMINEX CORPORATION                    BIO-RAD CORPORATION

By: /s/ RANDEL S. MARFIN               By: /s/ SANFORD S. WADLER
   ---------------------------            ----------------------------
Name:   Randel S. Marfin               Name:    Sanford S. Wadler
     -------------------------              --------------------------
Title: Vice President                  Title: Vice President
      ------------------------               -------------------------

- ----------

[**] Indicates that material has been omitted and confidential treatment
requested therefor. All such material has been filed separately with the
Commission pursuant to Rule 24b-2.

   5


                                    EXHIBIT E

                             SYSTEM PURCHASE PRICING


[**]

These System Purchase Prices will be effective until [**], after which time
LUMINEX may, at its option, [**] increase the System Purchase Prices effective
on [**] written notice to BIO-RAD, provided that such increases (i) may occur no
more frequently than [**] and (ii) shall not exceed (a) [**] during the [**]
period beginning [**] and (b) the [**] increase in the [**] beginning on or
after [**]. Any increase in the System Purchase Prices shall be effective for
all Luminex Systems ordered after such notice. [**]

- ----------

[**] Indicates that material has been omitted and confidential treatment
requested therefor. All such material has been filed separately with the
Commission pursuant to Rule 24b-2.


   6


                                    EXHIBIT F

                BIO-RAD CARBOXYLATED MULTI-ANALYTE MAGNETIC BEADS


[**]

LUMINEX will treat the Magnetic Beads to meet the required performance
specifications listed in the table below.

[**]

- ----------

[**] Indicates that material has been omitted and confidential treatment
requested therefor. All such material has been filed separately with the
Commission pursuant to Rule 24b-2.


   7


                                    EXHIBIT G

                       BIO-RAD MAGNETIC BEAD TOLLING FEES


[**]



- ----------

[**] Indicates that material has been omitted and confidential treatment
requested therefor. All such material has been filed separately with the
Commission pursuant to Rule 24b-2.

   8


                                    EXHIBIT H

                              BIO-RAD BEAD PRICING

                                      [**]


- ----------

[**] Indicates that material has been omitted and confidential treatment
requested therefor. All such material has been filed separately with the
Commission pursuant to Rule 24b-2.


   9


                                    EXHIBIT I

                                      [**]

Following are the mutually [**].  These Specifications [**].

[**]



- ----------

[**] Indicates that material has been omitted and confidential treatment
requested therefor. All such material has been filed separately with the
Commission pursuant to Rule 24b-2.


   10


                                    EXHIBIT J

                                      [**]



- ----------

[**] Indicates that material has been omitted and confidential treatment
requested therefor. All such material has been filed separately with the
Commission pursuant to Rule 24b-2.